That was arguably the nicest thing Jamie Dimon had to say about the cryptocurrency.

He even went so far as to say he'd fire any employees trading this cryptocurrency, calling them, bluntly, "stupid."

Now, Bitcoin can be volatile on a "normal" day, and it has seen massive swings in recent days, largely on news that China plans to clamp down on it. Nevertheless, Bitcoin plunged 10% almost immediately after Dimon's roasting.

Of course, this isn't the first time he's badmouthed Bitcoin – and I'm sure it won't be the last, either.

Here's the thing: Dimon is completely wrong about Bitcoin.

What's more, JPMorgan – his own outfit – and plenty of the other big banks are all over the digital currency and the technology behind it.

That means traders and investors who are keying in to Dimon's comments risk making a catastrophically expensive mistake.