On the contrary, we're in the position to do an incomparable disservice to the world. Companies buy exploits simply to buy the hacker's silence, and governments buy exploits to bolster their offensive military capabilities -- when we sell to them we're complicit with the damage they do.
Personally I'm of the opinion that the only responsible disclosure is full and anonymous disclosure.
There's nothing wrong with having a talent and wanting to make a living from it.