It really depends which billionaires. Believe it or not, some billionaires aren't bad people (probably). Billionaires are just people with a ton of money and power at the end of the day, and we should judge them on their actions, not their bank balance, regardless of our suspicions of how they got so rich.
However, if we could stick (for example) the Sacklers, Kochs and Murdochs in a sub and send it to Challenger Deep with just enough oxygen to get there and plenty of ballast, we'd definitely be doing the world a favour. These scumbags have a huge amount of blood on their hands, and while it would be better to see them in jail, we never will, so fantasising about their horrible demise is the most we can really do.