Give me one war where the instigators got more from it than they invested.

There is none. For oppressors always loose at the end.

It is funny how we pay attention to such laws as gravity, but we fail or ignore the laws about oppression. It is written:

“Indeed, those who conceal relevant truth spend their wealth to avert people from the way of Allah. So they will spend it; then it will be for them a source of regret; then they will be overcome.”
Quran 8:36

Indeed, Peace is a zero-waste venture.

As to war, it is always a loss even when it becomes a necessity to repel an oppressor.

By studying the history of the world, we realise that many warmongers, modern and old, are anti-theists, but some do wear the cloak of one religion or another, yet they are as far from true religion as one can be.