The
marginal cost is 0.
But don't you lose out on a lot of benefits of citizenship as well (visa free travel, etc.)? If you want to trade in US markets you are still liable for US taxes regardless.
As a US citizen permanently living abroad, I'm really annoyed at having to file, but I'm not even contemplating renouncing my citizenship.
Quite honestly, I pay slightly higher income taxes in the country I live in, and I'm happy to do it. If I were ever eligible for a wealth tax (besides the property tax almost all middle class people pay, which is very much a wealth tax), I would be fine paying it.