Very simple dear sir.
While it is true that SS is funded by American paychecks, what nobody wants to recognize is that the money is thrown into the general fund. So your SS funds go to pay for the military, infrastructure, medicaid - everything. Then when all of the government's bill are paid, they calculate the amount of money that the SS fund should have and allot that to the public.
It's all accounting tricks.
And as SS benefits increase, the funds put in from the 60s/70s/80s are expected to beat inflation and pay for those new found increases. And while the SS benefactors continue to outnumber the SS contributors, we're "expected" to keep pace with these new payouts.
But essentially, the problem comes down to the terrible financing job past administrators have done. Economic decline? You need to dip into more of the SS fund. War? Dip into the fund. It's like having a 401k, but not having a penalty on when you can touch the funds. It's just a overrated savings account at this point. But instead of concentrating the conversation on the wars/failed policies that pull money out of the fund, we focus on the age limit and benefits.