Compared to other underground genres of metal music, new metal can be considered mainstream music. Their popularity can be compared with other styles of pop music.
You'd be surprised actually, many people around my age discovered nu metal through tiktok and the genre has had a massive resurgence lately. It's probably the biggest metal genre for people born in the mid 2000s.
What I’m saying is if you liked it back then you may like it now, but I don’t think many people get into it 20 years later. No one is saying “I just discovered Linkin Park and they’re great” lol