I know what I should invest for :]

Personally I woulda sold it for a lifetime supply of my own freshly baked cookies- and since I would be soulless, lifetime would be infinite!

i dont think that works that way

The unrealistic can be anything I want it to be.. that includes soulless immortality.

I would personally sell it for a genie that gives infinite wishes, and no rules to this genie so I could wish for anything and everything.

That would be SMART :D
Maybe I would just go for the power of extreme luckiness/unluckiness, so I can win any lottery or pass any quiz :]