Of course the program is most regressive for younger workers, who pay the most and will get the least in return.
Social Security is in serious trouble, by the way, although it is not the driver of the current budget crisis. In just a couple of years the program goes into the red, and increasingly so as more boomers retire. The unfunded liability is around $8 trillion. That's serious money.
Social Security can never go bankrupt, and it can never be in debt.
This is wishful thinking. Social security benefits have been promised to a lot of people, and the money isn't there. It's all well and good to say they will just reduce benefits, but that's just a nice way of saying that they'll default on the liabilities.
In reality this is no different from Medicare or Medicaid, or the military budget, or anything else. Sure, we can in theory just reduce payout. The reality doesn't work out so neatly.
Social Security and Medicare are funded by payroll taxes. Medicaid and military budget funded from Federal income tax.
If you cut military budget 100%, you will save ~900 billions (or whatever the right number is) a year. If, on the other hand, you cut Social Security or Medicare, the savings are 0, because you will have to cut their funding as well. Surely, no one will pay Medicare taxes, if there is no Medicare exist, right?
Guess what happens to the rest of the money: It gets spent elsewhere. Social security buys US Government debt with any excess, meaning it goes directly into the budget. In theory the SS trust has assets, but in reality the money is gone. It's one account holding a bunch of IOUs from a second account, and both accounts are owned by the federal government.
http://economix.blogs.nytimes.com/2011/05/17/the-real-social...
And frankly, medicare wouldn't be if we killed the payroll tax cap. I never understood why it's ok for payroll taxes to be regressive.