Troll much? I would say what I really think of your opinion but mods would likely step in, so here is the polite version.
There are two reasons why a TH7 would try to climb into Crystal leagues... One is because their whole clan is doing a trophy push to see how high they can get to, and being part of a *team* they are doing their part to contribute. Clearly a concept foreign to you.
And secondly, the DE up there is damn good. Which makes it far easier to upgrade your BK and dark troops. I farmed 26k DE in about 3 hours on my way back down from there.
No-one is arguing that Crystal League is way too high for a TH7 to exist in for anything more than a short period of time. You get attacked the instant you log off, and when using expensive troops like dragons you will burn elixir like petrol. But there are perfectly valid reasons for people to try raiding above their comfort level, and the simple fact is that not everyone chooses only to get there by just searching for outside town halls, certainly I didn't anyways.
As for other people's estimates of how high certain town halls etc can go... bear in mind that what someone achieved one or two months or longer ago does not necessarily bear any relevance to the game today. That second inferno tower in the recent update and time ticking on since TH10 was introduced has made the game *very* different and much harder for lower town hall levels compared to before. There are an obscene amount of premmie TH10 bases out there that dominate the bases presented to you above 2000 trophies. And it is only going to get worse over time, making it harder and harder to reach a range someone says they achieved a while ago.

