>How is social security adding to debt when its funded by payroll tax?

Simple - the payroll tax doesn't raise enough funds to cover the full cost of the program. Even if it did raise 100% of the needed funds, that's still money Congress cannot tax a second time. At the end of the day, the government has two buckets: income and expenses. It doesn't matter whether some of that income is called "payroll tax", and some of it is called "income tax". Every cent raised through a payroll tax, is a cent that cannot be raised through an income tax, and visa-versa.

>Replace Medicare and Medicaid with a socialised 1 payer system as it would be much cheaper.

Yet...none of the advocates of a socialized healthcare system have ever put forward a real bill that can be rated by the Congressional Budget Office. Instead, they put forward shell bills which importantly lack any funding mechanisms.

> The numbers I saw was that the current system costs 48t and 1 payer system would be 32t.

The current system is divided between public and private spending. Even if you could reduce the overall cost to 32T, that's still a net cost increase on the public side. How will the government raise that money? The advocates for social healthcare never say.

The government borrows money from Social Security, and the government pays that money back with interest. So what you are complaining about is actually a transfer of money from the general fund into Social Security. And when we talk about the impending insolvency of Social Security, we're talking about the point at which this subsidy stops (because they won't have any surplus funds to lend), and the program is forced to cut benefits to match what payroll taxes bring in.