Biden isnt hopping in a time machine to take things away from you. Nothing is being taken from you. Someone else is getting something that you are not, that's all.
Governments raise money through taxation. 10k of forgiven debt is 10k more than needs to be raised in taxes.
Someone payed their debt, and then will be taxed more to pay someone else's too.
You might say, "but governments don't have to balance their budget", yet the US still has taxes. If money spent (and debt incurred) is irrelevant, why collect taxes at all?
Suppose everyone else on the planet is given $10B and you get nothing. Why would you be concerned? How could it be unfair? They're just being given something that you are not.