How do you get around paying the 15% of you Income that is taken out for FICA? If you add that in, then your effective tax rate is 20%. That's a lot higher than Buffett's or Romney's.
If you drop dead before you can collect then it is tax. The same can be said if they start means testing. Everyone's effective tax rate will be different. If live to 80, I'll come out on the plus side