JPMorgan Chase CEO Jamie Dimon has dumped on cryptocurrencies for years.

"I've always been deeply opposed to crypto, bitcoin, etc.," he said during a U.S. Senate hearing this month. "The only true use case for it is criminals," he added. "If I was the government, I'd close it down."

But this reprimand and the ones that preceded it – he called bitcoin a "hyped-up fraud" in January – are now very much a "do as I say, not as I do" situation. That's because JPMorgan is going deeper into the original cryptocurrency. On Friday, it was revealed that the bank will play a key role for BlackRock's proposed bitcoin (BTC) ETF.

JPMorgan will be one of its authorized participants if the ETF is approved, which involves "ensuring that ETF prices are accurate, and that trading is smooth, in all market conditions," according to BlackRock. In the multi-trillion-dollar ETF industry, few jobs are more important than the one JPMorgan will play for BlackRock's product.

Given Dimon's stance, if this isn't hypocrisy, it's close.

In the world of finance, the allure of profits has always had the ability to override morals, though Wall Street has embraced the ESG movement (short for environmental, social and governance) in recent years, giving clients the ability to steer investments away from investments deemed not socially responsible.

For at least now, though, the bitcoin hype is too much for the biggest U.S. bank – as well as other traditional finance players like Jane Street and Cantor Fitzgerald, which have also been named authorized participants for bitcoin ETFs – to ignore.