It's not good to invest all your eggs in one basket and hence people have invested in altcoins to have different coins in their portfolio. Investors earlier had to just depend on one coin and couldn't have a diverse profile due to which altcoins were created and not all altcoins are shitcoins and some are stable like ETH for example. Investors need stable crypto coins as well as BTC's fluctuations are too much to handle. Just because the market is bear since 2 years, we can't just disregards to success of bitcoins due to these altcoins.

Also, most projects have stopped because of the bear market and not because they lost interest. They are waiting for the conditions to improve to bounce back.