Simple. Heads of State get together and decide to what they want to happen. They have a whole range of levers to pull to manipulate markets.
> where most notably personal profit leads the market over political decisions
This is 100% wrong. I trade Forex daily and (a) political decisions drive the market and (b) we follow the market not drive it. Statements from say ECB, FOMC and reserve banks around the world etc all dictate what the currency markets will do.