Why aren't there big public celebrations anymore?

https://www.lesswrong.com/posts/q3JY4iRzjq56FyjGF/why-haven-t-we-celebrated-any-major-achievements-lately
From watching Miscavige videos, we've learned that Scientology is organized around huge celebratory events, which imply they are a fantastically successful organization. These events are all planned and managed by Sea Org members. In the last days before a Miscavige celebration, the Sea Orgers typically work around the clock.
In society at large, such celebrations have become rare or nonexistent. Like the huge festivities after the polio vaccine was developed, or the opening of the Brooklyn Bridge in 1883. Why is that?
I will gladly answer that question. It's because, compared to these earlier events, human progress has almost stopped.
In the extremely unlikely event that the scientists will get around to inventing a vaccine for heart disease, cancer, or degenerative brain diseases, THEN there will be a big public celebration again.
We seem barely closer to that happening than we were when the Brooklyn Bridge was originally opened.