I think about this from time to time. There are SO many altcoins out there, it is a foregone conclusion that a majority of them will indeed fail. Is that worthy of being called a scam though? Some may say so. If the developers do not put forth an effort, and live up to the white page and roadmap that was planned out...it would be fair to call them quitters/scammers.
Then, there are real deal scams 100%...like Bitconnect.
So, for me, there are 2 distinct categories...with one of the categories containing altcoins that could be argued as scams. The world isn't big enough for the number of coins being created, plain and simple.
I hope I am invested in the right ones, and I hope you are too.