Why do real-life arms dealers sell their high-tech weapons, rather than keeping it themselves and invading a poor war-torn country?

The ASIC manufacturers know that as more and more ASICs start mining, the network difficulty will go exponentially upwards. GPU miners will become like CPU miners of old. Soon you will need a 10 Ghash/sec rate just to earn 0.1 BTC/day. So ... they see the future and the writing that is already on the wall. They will make more profit selling the weapons rather than having the headaches of trying to run a poor country for themselves.