We play to reach the end game. While you maxers reach TH9 at 9 months, we reach there within our first half year. As many people already said, TH9 is the best TH (not for me), and there's no harm reaching there early and staying in TH9 for extended periods of time.
The "vast" amounts required is only applicable if you maxed, lvl 8 cannons cost the same whether you do it in TH7 or TH10. But getting offense up to speed does take a vast amount, but after it is done, it is totally worth it



