Sure some scammers has takend advantage of altcoin to scam ,damaging bitcoin as it is the main crypto,without them i belive bitcoin would be more valuable as the scamm projects would exist.
Yes but we cannot blame altcoins.
Alts are good way to join in, if you have good GPU you can join mining alts and this is same as you mining btcs, even better because you can earn more and faster. This was my case with mining DOGE coin, and NOBLE coin.