Billionaire Mark Cuban has always been cautious when it comes to bitcoin – despite being an investor in businesses built on cryptocurrency and even personally investing in bitcoin himself, he frequently warns others to be careful because he finds it to be a gamble.

Cuban has gone as far as to say he would "rather have bananas than bitcoin" because at least as food bananas have intrinsic value, he told Wired.com in September.

So what would it take for the "Shark Tank" investor to change his mind and comfortably support bitcoin?

"It would have to be so easy to use it's a no-brainer," Cuban said on "The Pomp Podcast" on Wednesday. "It would have to be completely friction-free and understandable by everybody first." So easy, in fact, that "grandma could do it."

"Then you could say it is an alternative to gold as a store of value," he said.

For one thing, bitcoin would have to become easier to use in payment transactions while shopping, he said.

"You've got to be able to spend it, because right now you still have to convert it for anything that you want. And as long as you have to convert it, you're still dependent on fiat [or government-backed currency]. No matter what you say," Cuban said on the podcast.

Comparing bitcoin to bananas again, he added, "I can trade bananas easier as a commodity than I can trade bitcoin. And I can still eat that banana before they goes bad, and get all my potassium for my workouts!"

"With gold, at least there's gold coins – I could use gold bars as furniture. But with bitcoin, it's virtual, and that's its beauty and that's its problem," Cuban said on the podcast.

"Now, the fact that we're arguing so much about it, and you have so many stands on bitcoin, that just proves the point that it's difficult," he said on the podcast. "And you can't spend it on anything."

Cuban says there are so many unusual parts of bitcoin, like "the halving" and "the mining," which makes it very complicated to understand.

"Blockchain is a great opportunity, but the reality is, we haven't seen blockchain applications really take off," he said on the podcast. "There's uncertainty with all the different types of crypto and arguments between them all."

But "to bitcoin's potential benefit, if everything goes into the sh----r because we're printing so much money and there's global implications, bitcoin has something to deal with and if we don't, bitcoin's got nothing."

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Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."