Here are a couple of simple changes to SS.
First, make the tax compulsory only for those not saving 7% of their income for retirement. For example, if you save 5% in a retirement account, then you pay a 2% SS tax.
Second, make it true to its name and make it insurance not a for-sure benefit (at least, for-sure until there’s not enough folks to cover it). So, even if you find yourself penniless after having saved 7% in your 401k, you might be eligible for the safety net. But, there may be some conditions even to that to encourage folks to be prudent with their 401k investments.