Are you a lawyer? Don't think you're right here...
Don't take legal advice from random HN threads.
This is a good point. While I'm glad they're starting to go after celebrities who tout scams, a lot of these people are "just" reading something from a card or tweeting something in return for a check. They really need to get the folks who contracted with the celebs and told them what to say, too!
If the person did decide to go to the SEC, here's what you'd need:
1.) A good lawyer (don't go talking to investigators without a lawyer)
2.) A sit down with the lawyer and the investigators
3.) ???
4.) Worry if the death threats are actually meaningful
A dozen crypto bros may not be too worrying. But you don't know who else got juice from the scheme. There were already unknown boxing promoters mentioned. Boxing is a dirty sport with real organized crime ties. And crypto is used to facilitate huge amounts of money laundering, which attracts criminals of all stripes.
Easy for random HN commenter to say go to the SEC. In real life, there are consequences that the person just doesn't need.