On whether or not you're an idiot for wanting to leave the US, that's a hot debate but a pointless one to have. Peoples emotions are just too deep.
I would say this: Cuba is a good example of the different 'phases' of migrants.
When Castro was rising to power, their smartest and wealthiest flew into Miami on airplanes.
When Castro finally seized power, their next smartest left in fishing boats.
When the remaining population finally realized that it was too late to leave freely and they no longer wanted to stay, their only option was to make a raft out of steel oil drums and hope they weren't eaten by sharks or shot by the Cuban Navy...
As far as the United States goes, I think we're in the 'leave on airplanes' phase. Don't worry yourself debating people who 'don't get it'. Just wish them the best as you leave them behind.
If you renounce/relinquish your citizenship, you have no further tax obligations to the US.