A huge number of voters are either collecting Social Security or counting on it for their upcoming retirement. Many of them actually have nothing else. You cut or kill Social Security and you WILL lose the next election. 68% of those 65 and older voted in 2018. 38% of women and 33% of men age 18-29 voted. It's still the third rail of American politics.
Doesn't matter if they are FOX News watchers and staunch Republicans. When you cut their income, you are out of there.