Bernie is saying it clearly in his own tweet, but he is too blind to see it: "income" is the crucial word here.
Elon is not "earning" $1 trillion (AOC is right on that part, ironically). Elon owns companies valued at $1 trillion, he built them.
The moment he sells his shares, it becomes income, and he will pay taxes.
Today, Elon Musk, a trillionaire, pays the same amount into Social Security as someone making $184,500.
If we end that absurdity and lift the cap on taxable income, we can make Social Security solvent for 75 years and expand benefits by $2,400. My Social Security bill does that.