Whoa, whoa, wait. I already explained it. The mayor cannot collect coins (triggers). Everyone else can. They go into coin warps (not available for mayor). There, they shoot coins down into a room only the mayor can enter. The mayor uses that money to enter a room only he can access, where he buys upgrades and defences for the base. It's a balance between economy, defence, spending and...er...blowing stuff up over at the enemy's base.