Doing so would make it really easy to trace it back to him, if he decides to make a trade big enough. The data of all trades on public markets is, after all, public.

Is it possible to make a substantial amount of money on such schemes while evading detection and subsequent prosecution?

https://www.marketwatch.com/story/to-catch-a-thief-how-nasda...

There are a couple offshore companies that let you buy/sell stocks with Bitcoin semi-anonymously. The problem is you can't short, so your attack has to result in pumping the stock: "Taking Twitter private at $420 a share".

You don't do it by selling TWTR one minute before the hack.

You use your brain a little. You prepare your positions months in advance, and hedge out market risks.

You can also use less regulated brokers in far away places and trade TWTR derivatives.

Ok but brokers aren't less regulated, exchanges are, and Twitter isn't traded on every exchange.

If you want jail time, insurance fraud is probably a tad quicker.

except that governments would quickly try to freeze the banks and stock accounts

There are millions of traders trading randomly (see r/wsb). Good luck spotting the one belonging to the hacker.

This is one information theory war against the FBI I can almost promise you would lose.