Bitcoin’s surge past $17,000 late last week reinforces an important economic theory: a rapidly-expanding asset bubble will always draw a crowd. But it should also reinforce fears about a situation that is not limited to a few foolish retail punters and a few swashbuckling hedge funds. This is a crisis for financial services.

The cryptocurrency’s rise is a source of much hilarity for most of finance, reminding us that you can always count on dumb money. But financial institutions — exchange operators, derivatives clearing houses...