They do because you still pay into the system but draw less from the system because you are withdrawing from your own savings!
"As a matter of fairness, I propose that future generations receive benefits equal to or greater than the benefits today's seniors get."
To that, I say there is no free lunch. The actuarial deficit cannot be closed for free. Either you increase risk to get higher expected returns, with a downside presented by the left side of the bell curve of results, or you raise taxes. Granted, I don't think Bush really meant what he said, but well, he said it.