The original maker of Viagra has not being ripped off. - of course they have. Money that was meant for the drug they made has gone to someone else. That is a rip off.
The fraudulent sale in no way affects the assets, inventory, or any other property of Pfizer. It's like you're claiming that they own the
potential sale, in which case they might as well sue anyone who intends to buy Viagra but changes eir mind before actually making the purchase.
Viagra was made to be sold. The buyer intended to buy their Viagra. The money they should have been paid is gone to a cloner. In their year end accounts, that money will not be included in the revenue figures so when they evaluate their assets, the return on investment will be lower.
That's a very serious affect. If it happens often enough, the return on investment will fall to the point where it doesn't make sense to do medical research and they will close down.