If I only watched YT on the browser sure. But I mainly get it so I can go without ads on mobile and on my TV. Yes I know there are apps like Vanced but I personally find it worth it not have to always look for workarounds.
I don't care about YouTube getting paid, but apparently YT Premium is lucrative for the creators (in comparison to ads). It's a very cheap way to support the people who make the content that you enjoy.