I think there is quite a bit of Follow ME/Follow you going on. I'm a Mini-Minnow here. I've stumbled on a few users with a huge number of followers, but then I look and see them following tens of thousands.
Here we see about 23% may be a Follow Back (23% = 12724/55346 followers divided by following).
Not with joanaltres, but with others, I find it odd to be following more than 30,000 but only started in the past month or two.