Investors, particularly millennials, have reason to be optimistic about the market, in spite of lingering pessimism from the financial crisis, Wall Street bull Tom Lee told CNBC on Tuesday.
"We have to appreciate what the last nine years looks like, because we had come out of a financial crisis," the co-founder of Fundstrat Global Advisors said in a "Squawk on the Street" interview. "We established a bubble of pessimism. And I think even this year, it's been popular for people to call the top, but no market top has ever been called."
As rising U.S. stocks push the S&P 500 to another all-time high, Wall Street bears warn one of the longest bull market runs in history is coming to an end. But Lee said solid fundamentals and rising millennial wealth means the bull market could continue its run.
"We've had attempts to really undermine and weaken the bull narrative around equities, and its been short-term. And I think fundamentals are really great, we have a lot of breadth and then things like small-caps rallying now are really bullish signs," Lee said.
Lee said the biggest reason the bull market has pushed on is because millennials, "the largest generation ever in history," are starting to hit their stride, make money and invest.
"They are just hitting their prime income years," Lee said. "The biggest reason we are in a bull market now is because millennials are making a lot of money."
Margaret Patel, managing director and senior portfolio manager at Wells Fargo, agreed that the bull market isn't quite done yet.
"We have never seen a period like this. I don't see this as a cycle where we will peak and then go down and have a big market correction. I think we are on a steady ramp upward," she said.
Patel said she sees continuing economic growth, higher equity levels and market-friendly interest rates that won't derail the economy, because this growth cycle is different.
"We really haven't had this growth due to an explosion in leverage, which we've had in previous cycles," Patel added.
Although investors, as well as the Trump administration, may not like when the Federal Reserve raises interest rates, it won't hurt the market, Lee said, because "history has shown in a period of accelerating growth, rising rates don't kill an equity market."
"I think last week has proven you've got to be looking at the market half-full," Lee said. "Between now and year-end, I think investors should be pretty optimistic."
The S&P 500 hit an all-time high Tuesday, trading above the prior intraday record of 2,872.87 it hit on Jan. 26. After the January high, Wall Street then took a dive and the S&P 500 hit its yearly low of 2,532 during the Feb. 9 trading session. The current bull market is on track to become the longest in history as of Wednesday.