Getting to the sun is actually really, really hard since you have to decrease orbital velocity by a ton. I think guillotines are a much more economical solution.
With that being said, I'm still onboard with giving it a shot in the name of science.
Should just cap out. Like once you get to a certain point the rest of that money is a tax rate of 100% then that money goes into making things better for everyone or a ubi
"Congratulation, we have noticed that you are only earning money as a way to get a better highscore, this means that you gathering further wealth for your own sake is pointless.
This means that any further wealth you gather will be sent to the usefull projects and organizations where it can do the most good.
But don't worry, your wealth highscore will still be recorded as normal.
By reaching this milestone you can take pride in knowing that you have done amazingly well, and as a mark of this milestone, you will get a statue of yourself in the 'Hall of financial heroes' to truly know that you are a great person."
No need to waste their skills by killing them, just let them keep working doing what they love, but have their work benefit society instead of lining their own pockets.
You obviously need to stroke their ego and play them up as much as possible, but that is a small price to pay to keep the money train going into society.