I read a ton as a kid but for whatever reason didn’t really go in for entire series. The first series I remember saving up and buying with my own money was the Dragonlance Chronicles books.

This is certainly anecdotally true with all of the people I know. I’m part of a discord server of local folks with common interests and we talk books on there sometimes. Me and one other guy read 15+ books a year. There are a couple of people who read 3-5 books a year. Everyone else (~40 people) does not read.