"We tend to stay away from assets that don't have underlying economic value," Buckley told CNBC.

There’s plenty of interest, but not much serious support for a Bitcoin ETF, judging by comments from ETF providers and others at this week’s Inside ETFs conference.

Vanguard CEO Tim Buckley, for instance, said Monday in an interview with CNBC: “You will never see a fund from Vanguard on Bitcoin. We tend to stay away from assets that don’t have underlying economic value. They don’t generate earnings or cash flows.”

The head of the fund giant is not alone.

We are “early” in the Bitcoin futures cycles, which means the launch of Bitcoin ETFs will take time, Hunter Horsley, founder and CEO of Bitwise Asset Management, told a packed conference session on Tuesday in Hollywood, Florida.

“The SEC got about 30 comments regarding custody, liquidity, etc.,” Horsley explained about the regulator’s recent decision to ask ETF manufacturers to withdraw their applications while it studies the asset class.

“There are lots of good questions that have to be addressed,” he added. The possible launch of Bitcoin ETFs in 2018 is “really unclear.”

Jan Van Eck, CEO and president of VanEck, says regulators can’t wring their hands for too long.

“There are 15 million people invested [in this asset class], and it is [largely] unregulated,” he said. “What are the regulators going to do? Can we continue with unregulated exchanges? We are waiting.”

Bitcoin’s value, Buckley told CNBC, “is based [on] scarcity and an artificial scarcity that’s out there. It’s really tough to imagine where the long-term return comes from other than speculation.”

But in comparing Bitcoin to gold, another asset Vanguard avoids — saying it lacks clear economic value — the fund-family executive indirectly pointed out that investing is clearly in the eye of the beholder.

For the moment, judging from the crowd of over 2,000 attending Tuesday’s cryptocurrency panel, advisors and investors seem enchanted with the digital currency.