I also use to have the attitude that I should be able to run 50's a lot, but I have never broken 43. I guess I just thought someone who can do occasional 3 packs in the sissy games could get 50 at 14.1. But when you think about it, a 3 pack of 8 ball is only 24 balls, and at least 3 of those were uncalled lucky shots off the break

So you really can't beat yourself up about not approaching 50. You don't need to be a 6-pack runner in 8 ball to reach 50 in straight, but you do need to play pretty sporty.
These guys who hit 50's and 70's and 100's on this forum play REALLY sporty and it might seem like there are a lot of them, but this forum is kind of the #1 spot for english-speaking pool nuts... so if only 20 guys here talk about running 100's, that's probably 20 out of many thousands of people.
I also read once that some actual pro level straight pool players only average about 8 balls in league. That sounds too low to believe but it includes every safe they ever played and every break and every time they had nothing to shoot at. Knowing that makes me feel better if I "only" get 20.