Well, I guess the short answer is I find it pretentious.
I get that.
FWIW I have to assume that a good part of the price on that triptych is the subject matter. I.e. a Bacon painting of Freud is sort of like a Ditko drawing of Kirby or a Kirby drawing of Ditko, if such things were to exist.
Even if such drawings were not esoecially well realized pieces of art, they would command a high price because you have one comic art god drawing the other. So too with this picture of Freud by Bacon.
142 million is a lot of pretentiousness. If it was Norman Rockwell, N.C. Wyeth, or Maxfield Parrish, then I might be more understanding.