Because you could have waited on paying off your loans, and under Biden's plan you would have got $20K handed to you. In that case, the decision to pay off your loans would have carried an opportunity cost of $20K to you.

"I hope others get forgiveness." Loan forgiveness does not mean the debt magically disappears; it means somebody else is paying it. That "somebody else" is a taxpayer, who might be a plumber or Walmart clerk who never went to college. "Their gain" really is somebody else's loss, who likely makes less money than the beneficiary of loan forgiveness.