even rich ones need to keep working to make sure they dont run out of it
Well-invested money, and you no longer need to work. We're talking about millions of dollars here.
If you are thinking of stopping at a certain point in life just because you are rich enough already then this is what sets you apart from the wealthy ones. When you are wealthy, you do not stop. You keep going and improving. Since you already have more resources than ever before you can make more now that you are rich. If your money suddenly runs out and you have already stopped working then where will you be getting money to survive?
Ironically it wouldn't have mattered when they stopped as both people made their OPSEC mistakes early on in their careers. They would have been caught and charged, regardless if they decided to retire early.
You are correct. The only difference is maybe there would have been less grave charges but they would have been imprisoned anyway. Maybe they thought of that too. If they were gonna get caught eventually, might as well make the most out of it, right?