MABS, like vaccination, are actually covered by the US government's pandemic free stuff policy. The hospital might charge you (quite a lot) for the IV infusion, but the MAB itself is paid for by the feds. IF you can find it, and IF you qualify, and IF your disease progression permits it. Most people don't even know about it, so won't do the leg work to find it. Qualification is pretty liberal now: If you are at risk of serious Covid it's enough, which is fairly subjective. Not hard to find a doctor who will agree, but that takes resources most people don't have. Of course, if you are rich or connected, you have people for that.

Timing is essential. Eight days after symptom onset, it does nothing for you. Five days after, it helps a little. You probably won't die but might wish you had. Right after exposure is ideal. Very likely you will be asymptomatic. Prophylactic use works for about 3 months, but I think it's Merck that has a MAB in trials that works for one year. $$$$$!

We're flying electric helicopters on Mars yet you can't turn on your clothes dryer in Texas. That's because scientists are in charge of Mars, and Republicans are in charge of Texas.