The FICA tax is based on income (in 2017) up to $127,200 because recipients only get benefits based on income up to $127,200. I don't know of anything more fair.

Perhaps more of Larry Ellison's $184 gazillion income could be taxed -- requiring a rewrite of the law to include capital gains, dividends and other forms of income -- but then to be fair he'd have to get more benefits. Or are you suggesting you're entitled to more of other people's stuff?