If you have "no presence at all" then you either have no money, in which case you can't really afford entering it (in this case, anyway), or you have the money, but then the above rules still apply. Effectively it would be better to market your mediocre product to physicians than to kill the cash-cow.

Also, large risks are actually typical for this type of research. It's expensive and risky, so it has to give really large rewards. Research for completely new cures is even more risky and expensive, and the rewards are smaller.