Exactly. Most altcoins are extremely overhyped by their developers. Their main claim is that their cryptocurrency is a lot faster and much more scalable than others (when theoretically it's not). Once people realize that such cryptocurrency is just like others, they head back to the most prominent altcoins on the market. Usually, the intent of most developers is to generate hype in order to pump their cryptocurrency massively across the market. But when the time comes to determine its reliability, and usability, it fails altogether.
That's why, I believe that only a select few altcoins will survive in the long term. Useful ones are not based on hype, but rather real innovation and development. Ethereum, NEM, Cardano, and Monero fit the bill nicely. The top 5 cryptocurrencies in market cap will do, but there are a few out of this range which are quite worth the investment nowadays. You just have to do your own research to determine how useful an specific crypto is.
Nonetheless, time will tell us what will happen with most cryptocurrencies' adoption in the mainstream world. Just my thoughts