Part of the issue is that the wedding market it just outrageous. The average cost of a wedding or attending one is out of control. The industry has done a good job marketing it. Social media "keeping up with the joneses" or comparisons is not helping either. It adds yet another piece of pressure so I'm not surprised that less people are jumping head first into it.
>cost of... ...attending one is out of control What costs are associated with attending a wedding?
What other commenter said, plus covering bachelorette/bachelor parties (groom and bride don’t pay). Wedding gifts. Where I am from and you’re being accommodated- it’s kind of expected (and part of etiquette) to include cash with your gift to try to cover hotel and dining costs for yourself.