Curing cancer will be infinitely more profitable than a lot of things, for the investors, but that doesn't mean they will be willing to pay engineers more than pure financial manipulators, even if they are able.
The only reason investors would enter the picture is if the engineers preferred to take a smaller cut upfront. Keeping with the marshmallow experiment theme, that is them choosing to eat the marshmallow instead of waiting for the desired treat offered to those who wait.
Indeed, that is the likely scenario as humans are greedy. People generally don't have the will to hold out for the bigger rewards, they want instant gratification to quash the feelings of their greed in the moment. They don't have to choose instant gratification, but if they want to then I suppose investment helps ensure that they still work on something useful when instant results cannot be seen.
