Instead of MLB/NFL, check out summer or arena leagues.
Things like MLB/NFL games have greatly outpaced inflation. One reason people keep paying for them (aside from other obvious factors, like love of the game) is because we have been conditioned to believe that they are things "average" people can afford them when in fact that hasn't been true for a long time.
Even if sports ticket prices didn't outpace inflation, the fact is that 50 years ago being at the stadium was the best way to see the game. Your other alternative was a tiny, balky TV or radio. These days you can see them at home in HD on a giant screen that would have seemed like science fiction 25 years ago and in fact, because of cable bundling, you may already be paying for this privilege even if you don't want to.
(edit: There are still things that are special about the live experience, but the home experience has become massively better than it used to be)
So like collecting physical music, or attending movies in movie theaters as opposed to Netflixing them it makes some level of sense for live sports attendance to migrate from "everyman activity" to "premium niche thing for diehard fans with disposable income."
This is unfortunate in many ways, and it is a loss, but it does not necessarily equate to a degradation of average quality of life. That would only be the case if average people no longer had any affordable leisure options ...if there were no new affordable to replace those which migrated upscale.
(FWIW, I say all of this as a sports fan who does enjoy attending some games each year)