For the same reason they sell shares below the ask to those of us who support the SP by buying at the ask. The MM's are crooks and are in cahoots with the whole short selling scheme. Without their involvement, it doesn't work. What the shorts don't understand YET is that there are a whole bunch of shareholders who continue to buy at these ridiculous prices. They'll never get out of their hole at this pace. As a famous short said to me in a PM a couple years ago,"we own you. stealing all of your money". I wonder how that effort is working for him and his cabal today. Looks like we own them, to me.
Eh, but what do I know. I'm just a dumb old jarhead, right?