that is not what leads to the devaluation of a cryptocurrency.
for some reason people only see half of the very popular basic economic concept called "supply and demand". but it is two forces working against each other. what you are talking about here is only the supply part and because all those altcoins have 0 demand (they are useless) the forces against the supply are nonexistent so the price of them keeps going down.

so how to fight this?
simple. create useful cryptocurrency and then set the supply of it in a way that can match that demand.