Is it understandable to leave your kind friends to fake popular ones?

I don't know why I did it but I did it.. I was new to that school and I met this group SPK, they are really cool for me and I love em but the others don't think so. Like the mean girls often makes fun of them and just you know. Umm so I suddenly stopped going with them at lunch and join these other two girls, the other one became prom queen and the other one is like the leader of the military training there. I've become their bestfriend then after a few months I left them and started hanging with the mean girls who got enemies and stuff and often makes fun of other people. I don't like them at all but hey that group consist of fakes so why not be fake to them? School's over so yea, the spk and my former bestfriends still is my friend now but the mean girls. Still don't like em.. I realized that the people who was really true to me was the spk and they're fun for me. I love em... I'm transferring so that I don't have to choose which group to hang anymore but my birthday is coming up so I think I'm gonna spend it with SPK.. My question is it understandable to leave your kind friends to fake popular ones?