You run that risk with ANY type of insurance.
Except with insurance it's generally my choice. I can choose which provider I want, how much coverage I want etc. With social security I can't choose any of that.
Then if I remain a permanent resident and 20 years from now decide that I want to move to, say, Germany, well there goes all my social security contributions. It's not wasted because I never had a need for them, it's wasted because the US government requires perm. residents to live here in order to collect the benefits they paid for (it's automatically deducted from your paycheck whether you like it or not).
Yes I can become a citizen and not have to deal with that, but then I'm subject to double taxation if I ever move abroad.
To briefly explain SSA it's something everybody who works in the US pays into. It's automatically deducted from your paycheck and the amount varies based on how much you earn. Then when you turn 65 (?) you can start to collect benefits from it (ie the government sends you a check every month). What's funny is if your benefits are quite a lot (ie you had a high paying job) you then have to pay taxes on those benefits...