Here are the top 5 things people wish they hadn't spent their hard-earned money on

Whether it's weekly Thai takeout or an air purifier you never took out of the box, most people have buyer's remorse about something.

Regret purchases tend to come in three types: things you never used; habitual things, like restaurant meals or drinks you no longer get any value from; or expensive things that kept you paying for a long time. In the Invest in You Spending Survey from CNBC + Acorns in partnership with SurveyMonkey, respondents pointed to clothes, alcohol and meals as purchases they came to regret.

But it's those expensive things — cars, timeshares, RVs — that are real pain points.

Failing to realize the total costs of ownership is one of the biggest financial mistakes people make, says Ric Edelman, founder of Edelman Financial Engines. In other words, you look at the monthly payment on a new car without factoring in the costs of insurance and maintenance. You may not look into whether a car has a record of extensive repairs or what its gas mileage is.

"Most SUVs and trucks get very poor mileage, and when people buy when gas prices are low, they don't give it much thought," Edelman said. "But the difference between 15 and 30 miles per gallon literally doubles your expense for transportation for fuel."

Life is too short to spend time beating yourself up over past mistakes. "Always look for the lesson," said Susan Webb-Trujillo, 58, who says she has no regrets over past financial missteps. "I've also learned it is pointless to try to recoup any monetary loss if an object no longer fits a need."

Let go of how much you spent, says Webb-Trujillo, who works in sales in northern Las Vegas. "It is easier to remind yourself to not do the same thing again."

Here are five purchases that consumers regret the most.

Vicky Morales, 39, says she would never, ever again buy a timeshare.

Vacation purchases can bring a lot of bitterness.

Add confusing terms and the high-pressure sales tactics from companies that sell timeshares and you've got yourself a perfect storm of buyer's remorse.

Morales, who works with mortgages in southern California, bought into a large chain's points system while on vacation in Hawaii in 2006. The presentation was tantalizing but confusing. "I was so misinformed by the way they sold it," she said. "They offered us dinner and a lot of perks, and at the end I got $500 cash."

The points system Morales bought was $10,000 — closer to $13,000 with interest charges. The salesman didn't go over the contract, and she wasn't aware of the annual $600 fees.

Morales had second thoughts when she returned home, so she called the salesman to cancel. But he persuaded her not to because it would reflect poorly on his performance. "I was young, and didn't want him to look bad," she said.

As soon as Morales was finished paying for her timeshare, she put it up for sale after using it only a handful of times.

"Definitely don't do it without doing the proper research," Morales said. She hopes to help prevent someone else from buying into one.

Over decades, monthly car payments can add up to a shocking amount.

Jodi Furman, 45, thought she was doing everything right. She and her husband always had fairly nice cars — certified pre-owned ones — starting in their 20s. They shopped around. They made sure to get the best financing rates.

But Furman, a health-care recruiter in Minneapolis who has a personal finance blog, recently calculated just how much they'd spent.

"It's a little stunning to think it's in the nature of $200,000," Furman said. "I'm a little sick to my stomach, honestly."

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Furman always had thought of car payments as a fixed cost.

Her lightbulb moment came when she paid cash for a 10-year-old car because she wanted to lighten their credit load to qualify for a mortgage. "I figured I'd use it for five months and then trade it in," she said.

Within a few months she had saved about $4,000 on car payments and lower insurance — without lowering their coverage — and, she says, the car was still worth about what she'd paid for it.

Wedding expenses can look very different years later.

"Given the choice of spending $30,000 on a wedding or for a down payment, brides routinely choose the wedding," Edelman said. They routinely express regret over that nuptials tab later, he added.

At the time she got married, Ashlea Beers, 35, says she was very proud of how she and her fiance managed to rein in costs and spend just $5,000 for their wedding. But more than 10 years later the Denver stay-at-home mom says a great honeymoon would have been a much better way to spend the money.

"You need to focus on each other," said Beers. If you need to choose, a honeymoon is the better way to celebrate a relationship.

As a former wedding coordinator and etiquette expert, Elaine Swann, founder of the Swann School of Protocol in Carlsbad, California, knows a thing or two about wedding costs. Among the first things she'd have a bride do is put together a realistic budget. Otherwise, you've got a train that's left the station and is roaring along.

Instead of starting with the number of guests, work backward from the amount of money you'll be able to set aside by the date of the wedding. "That will give you a good idea of the type of wedding you can have," Swann said. "Don't borrow, and don't go into debt."

"Knowing everything I do know, I wish we'd taken the money and eloped," Beers said.

Allison Hale, 33, was moving across Texas to Austin. Inspired by the tiny house movement, she and her husband thought it would be fun to do something different when they sold their house, so they gave away most of their belongings and bought a huge RV for about $35,000.

"We loved living in an RV," she said. What they didn't love: how expensive and difficult it was to find parking.

The family stayed at lake resorts in the Austin area and, on top of the monthly payments and insurance, paid around $1,000 a month in resort fees.

It was a good experience, and Hale says their young sons loved it. Then they left the RV for a few days, accidentally leaving the water on, causing a huge amount of damage.

Many regard RVs as second homes, and the tax code treats them that way, too, says Edelman.

"The problem is that homes tend to rise in value and RVs tend to fall in value," Edelman said. "They're not built to last 50 to 100 years the way houses are."

Hale's vehicle is now worthless, but they are still on the hook each month for close to $1,500 for financing, storage and insurance.

"Even finding someone to fix it has been a challenge," Hale said.

If you still think an RV is for you, Hale has this advice: Buy something you can afford, and pay cash. Be very realistic about where you're going to put it and where you can afford to put it. Have an exit plan — don't simply think you'll put it in storage. Know that even with good insurance, you can still be liable for various expenses.

The top homeowner regret is underestimating how much it costs to buy and maintain a home.

Twenty years ago Kathy Strand, 47, bought a three-bedroom house in Parkville, Missouri, but now says she would probably rent if she had it to do over again.

Strand, an instructor, found homeownership time-consuming and expensive. "The house was stripped of everything," she said of the previously owned property she bought. One bedroom held a hot tub, and the formal dining room sported an enormous bar. "I didn't anticipate all the work and living there through the renovation," she said.

Strand didn't consider school districts at the time of purchase.

School districts definitely count, Edelman says. "You're usually better off buying the least expensive home in a nice area," he said. "Most people who buy homes have school-age children, and the quality of the school district is of paramount importance to them."

Strand says she'd now look more carefully at an area's home sales. "I was looking to buy in another area," she said. "Houses were listed, but they weren't selling.

"Even now this house requires a significant amount of maintenance to keep it up," Strand said. Any appreciation in value will simply cover the costs of living there.

Compared with renting, owning a property is life-changing. Strand was surprised at how much of her free time went into maintenance and home tasks. "It's almost like having a second job," she said.

Check out What entrepreneurs like Daymond John and Ryan Serhant learned about money from summer jobs via Grow with Acorns+CNBC.

Disclosure: NBCUniversal and Comcast Ventures are investors in Acorns.