That is the key tight there. You can kill as many as you want but if they make $10m at a pop, it won't matter.
Sure it will; you've just got to make sure you want to kill them all. If you're quick and visibly successful, you'll do fine.
I can think of plenty of things I might do for $10,000,000, except for the fact that I would have less than a .01% chance of surviving any of them long enough to even accept the payment, much less spend it.