Bitcoin, Cuban said, is "a store of value...that is more religion than solution to any problem."
And bitcoin or any cryptocurrency will not replace fiat, or government-backed, currency, he said.
"No matter how much [bitcoin] fans want to pretend that it's a hedge against doomsday scenarios, it is not," Cuban said. "Countries will take steps to protect their currencies and their ability to tax, so the more people believe this is anything more than a store of value, the more risk of government intervention they face."
Those who argue in favor of bitcoin often say it is a hedge against inflation and the U.S. dollar, and that it will survive any economic or infrastructure collapse (except for downed internet), comparing it to gold.
Cuban agrees bitcoin is like gold in that it is a store of value, but because by its code the supply of bitcoin is limited, as demand fluctuates, the price will be volatile. "But," he said, "as long as people accept [bitcoin] as a digital version of gold, it's investable."
Investable, of course, doesn't mean it's a sure bet. Though Cuban himself has previously invested in businesses built on cryptocurrency and even in bitcoin, he frequently warns against it, calling bitcoin a "gamble." And when it comes to gambling, you need to be prepared to lose that money.
He reiterated the point to Forbes: "[Bitcoin] is what it is, something that enough people have agreed upon is an investable asset," he said. But "a banana has more utility, potassium, is a valuable nutrient to every person on the planet."
For the investor to change his mind about bitcoin, "it would have to be so easy to use, [like] it's a no-brainer," Cuban said on "The Pomp Podcast" in April.
"It would have to be completely friction-free and understandable by everybody first." So easy, in fact, that "grandma could do it."
Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."
Correction: This story has been corrected to reflect Cuban's quote that bitcoin is "a store of value."