One of the vanishingly few things I agree with Donald Trump on. If it weren't for social security, millions of seniors would instantly fall into poverty. Not every worker in the economy has access to a 410(k) plan. So, Social Security acts as a means of forced-saving for retirement for everyone. If we didn't do it this way, we'd be paying for seniors in other ways. Kicking the 65+ crowd to the curb just isn't realistic.
That said, everyone from ages 0 to 125 is being hit with a cost-of-living crisis due to 40+ years of failed Reaganomics, and we should re-design economic policy with everyone in mind.
In order to minimize the impact on the young, I would actually support expanding Social Security to the 0-18 crowd to give them a nest egg to use for certain qualified expenses that often occur early in life (college, homebuying, child expenses, marriage).
Who pays for all this? Easy, the rich do. If you're worth $2 billion today then tomorrow you might have to be worth $1 billion. Boohoo.