Yes, it is. Everyone pays into the program, the government pays it out to people. You don't get your own money back, you get somone else's. The money you paid into it is long gone, payed out to somone else long before you're eligible to receive it back. You don't get back the exact amount you pay in, you get a guaranteed amount for life that increases to keep up with cost of living/inflation.
That's exactly how socialism works. Everyone pays into a government fund, and the government disburses it as it sees fit. You dont get what you pay in back out, you get a portion of what everyone pays in.
If you don't believe me, do some research. I'm happy to be proven wrong, so long as there is proof.
Social Security is a socialist program that basically everyone in America is okay with having. There's nothing wrong with that.
How social security (and many of the socialist governments) are (mis)managed is a whole different topic