As founder of an altcoin, I can only partially agree with the OP. I agree that 99% of the coins are worthless, or worse scams.

There are two kinds of altcoins being developed:

1. Those that think they have some compelling new technology and can replace bitcoin - hardly likely. Those are the ones that crash & burn every week as next week's "technological breakthrough" arrives.

2. Niche coins, designed to fit a specific community - unfortunately those are mostly scams as well, but there are legitimate ones

When Paypal/Bitpay/GoCoin started accepting, not only bitcoin, but Lite and Doge, the market dynamics changed. I think the crypto market will move towards only a handful of coins being used, the overwhelming majority will be bitcoin, but the users will pay with the coin of the community they feel connected too. For example, if they like the Doge community, they will use it instead of BTC.

So the alts that survive will be those who build a real user community, and that is not bad for bitcoin, as these user communities will bring more and more users to crypo. In our case we have introduced many, many people to bitcoin, since they need bitcoin to buy our coin.

Why could these users not just use bitcoin? Because they are not connected to the cause (the revolution of bitcoin, the reaching the unbanked, saving trans fees, etc), but they are passionately connected to their own community.