The major entitlement spending is for Medicare and Social Security. People are entitled to Medicare and Social Security because they paid for them all their lives.
Do you propose that the government not pay people the benefits they paid for as part of a contract?
That would be like buying health insurance from a private company, and having them decide not to pay you when you get sick and need it, because that would be a good way for them to save money.
You are not prepaying for YOUR FUTURE befits. You are paying for the people getting benefits NOW. Your money does not go into your special "Lock Box". You are paying for your grand parents and parents. Your kids and grand kids will pay for you. It really is a ponzi scheme.