The amount of the debt is really irrelevant since SS is a pay as you go system. We don't need a SSTF, just the fact the full faith and credit of the USG to pay the benefits due. SS represents an unfunded liability of $18 trillion.
Regarding you number of workers supporting the system, that is solvable. Reduce taxes. Cut the spending and quit scarfing the present surpluses. That will cause employment to increase. Ergo! More working to pay into the system. Simple!
It is a matter of demographics. We are an aging society. 10,000 people will retire every day from now to 2030. By 2030 one in five residents of this country will be 65 or older.
Bureau of the Census: An Older and More Diverse Nation by Midcentury
It is not an unfunded liability. Millions of people have, along with their employers, paid into the system. To spend the surpluses which the SS system is still generating is tantamount to thievery.
But if you don't value your income and work, you are an easy mark for the thieves. I have a bridge somewhere I would like to sell you. I don't own it, but for you, what does that matter?