Social Security used to be a LOT more limited in scope so it wasn’t originally set up as a Ponzi scheme. Take a look at the original meaning of what work was and you’ll see that it was narrow in scope. Government workers weren’t originally entitled to it for example.
SEC. 210. When used in this title-- (a) The term “wages” means all remuneration for employment, including the cash value of all remuneration paid in any medium other than cash; except that such term shall not include that part of the remuneration which, after remuneration equal to $3,000 has been paid to an individual by an employer with respect to employment during any calendar year, is paid to such individual by such employer with respect to employment during such calendar year. (b) The term “employment” means any service, of whatever nature, performed within the United States by an employee for his employer, except- (1) Agricultural labor; (2) Domestic service in a private home; (3) Casual labor not in the course of the employer’s trade or business; (4) Service performed as an officer or member of the crew of a vessel documented under the laws of the United States or of any foreign country; (5) Service performed in the employ of the United States Government or of an instrumentality of the United States; (6) Service performed in the employ of a State, a political subdivision thereof, or an instrumentality of one or more States or political subdivisions; (7) Service performed in the employ of a corporation, community chest, fund, or foundation, organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes, or for the prevention of cruelty to children or animals, no part of the net earnings of which inures to the benefit of any private shareholder or individual. © The term “qualified individual” means any individual with respect to whom it appears to the satisfaction of the Board that- (1) He is at least sixty-five years of age; and (2) The total amount of wages paid to him, with respect to employment after December 31, 1936, and before he attained the age of sixty-five, was not less than $2,000; and (3) Wages were paid to him, with respect to employment on some five days after December 31, 1936, and before he attained the age of sixty-five, each day being in a different calendar year.