Except they actually serve a purpose - The combination of features (borderless, trustless money transfers) combined with a growing network effect enhances the utility - You're confusing an adoption curve with a bubble.  The price will of course overshoot and then correct, the question is the overall adoption trend.

This is different from new coins that add nothing new except speculative potential for people who buy them early.  With bitcoin there is the network affect and the aforementioned utility, what do new altcoins that change nothing bring to the table for the non-early adopter?   As far as I can tell nothing.   Each time something succeeds, the bar for anything that would take it over gets higher.