HN user
There are many reasons. Yummyfajitas mentioned two very good ones:
"Marriage is cheaper than being single due to economies of scale (a lot like having a roommate) and having a more stable income source (assuming 2 earners, it's unlikely both will simultaneously lose their job)."
I would also add, as equally important: support network.
I'm sure that there are more I can't think of, although they are likely related to one of those listed already.
The article is purposely misleading. At best its entire premise is concluded on one small report that only looks at one source of data. Even the article admits: "To be sure, the parallel movements of economic inequality and marriage inequality do not prove that the former causes the latter."
The truth is that there was some correlation always - that makes sense with what I said, which is smarter people are going to do smarter things like marry and make more money - but the extreme difference is today, not 130 years ago. This extreme and growing difference is due to the toxic culture being promoted.
The development arresting, pro-promiscuous culture - that is blatantly promoted almost everywhere.
Simple:
1) Richer people are mostly smarter. Smarter people see through the toxic culture and seek to marry.
2) Wealthy people are often so because they do things that help build wealth and success, Ie. marriage. Smart people descended from smart married people are more likely to follow their parents warnings about the destructiveness of the toxic culture which attacks marriage.