3) FDA approval (including clearance of manufacturing process)
4) Competition from other generics
5) Slow expansion of overall market
6) Actually profit on the product (sales > COGS)
There are probably others that I did not consider off the top of my head.
However, this risk is minuscule compared to the risk of R&D that Amarin went through with the risk of REDUCE-IT, as well with the recent FDA approval process.