There are two things you might want to consider;
1. The game is build with strong emphasize on offense. Decent players of equal TH level should be able to happily raid each other. You can not depend on your defense all the time. Even a maxed TH get 2-3 starred.
Relying on your defense alone is like relying on the most unreliable thing. And the more resources you hold, the more you'll attract others with higher quality troops to raid you. Eventually you'll get raided by someone who's strong enough anyway. People failing a raid in most case is of their own carelessness, not because of the defensive advantage of their target.
2. This game does not rewards defense. There are several thread which address this already.
You get a failed raid that only get one or two of your storage. So, what's that mean ? You get nothing other than you become weaker for the next attacker. Your castle troops are gone. Your barbarian king gone. Traps gone... So you'll get raided again. Even if you still manage a defensive win, each subsequent raid will become more and more punishing to your resources.
See to it as, which one is better for a premmie TH to be 3-starred, get 16 hrs shield and be done with it. Or... A maxed TH to be raided 37% three times, has the de storage zapped twice and eventually 2-starred after all the traps and cc troops were gone ?





