There is plenty of loot at TH9. The problem is that at TH8 you get access to more loot at lower THs, when you upgrade this is gone. Upgrading for the the purposes of getting more defence is useless, since when you upgrade too fast you just become a better target for other TH9s and you probably can't, successfully, loot other TH9s, or you have trouble sustaining your builders. So, its not impossible to recover from a prematurly upgraded TH, its just recommended that you don't do it.

