I have a fun story for y'all about why I love Britney:
When I was in third grade, her debut album dropped. Yes. I'm 25. My mother bought it for me for Easter. We had show and tell in school, and my teacher asked everyone to talk about what they did/got for Easter. I told her about getting the album, and she asked me to sing a few of my favorite songs from the album, so OF COURSE I did. I performed snippets of BOMT, Sometimes, and From the Bottom of My Broken Heart (my trinity). My teacher loved it so much, that she had me sing again in front of all the parents at the end of the year get-together.
So even though I may not stan for her as hard as I did when I was 8, she will always have a place in my heart.
I guess it actually does make sense for Britney's fanbase to be older, since she debuted in 1999. A lot of Mariah's fanbase is older, as well, but there are a lot of younger ones. I'm sure Britney has a lot of younger fans, too, who understand her impact.