When I was in SV during the dot com boom, the combination of the gender imbalance in the area (I seem to recall it being about 80 single women for every 100 single men between the ages of 20 and 29), the lack of having any firm tie to the area (no hope of getting a house - it was all single bedroom apartment rentals) and the, lets call it "cost of courtship" - it really didn't make financial sense to invest too much time or heart into dating and trying to get married.
Later and elsewhere, the expectation that I'd be the single source of income for a family of a previously divorced woman and step kids was a distinct turn off for trying to pursue a relationship later.
Having siblings get married, have kids, and get divorced and the continued difficulties with that a decade later makes marriage and kids even less appealing to someone who has never had either to see what benefit they provide (yes, I'm sure they do - I just don't know what it is in relationship to my own investment of time, money, and heart).
Now, I'm going to say I'm a grumpish graying beard who's too set in his ways.
Sure, it would be nice to have a partner in life to take some of the household decisions. Managing a house as a single adult is more difficult and expensive than doing it with a partner, but the degree of change that I am expected to make accommodations in my life just makes it feel not worth it to even try to pursue.
And as I write this, I'll note that I do have at least a bachelor's degree, I am employed, my salary is well above the median earnings reported, and I am not financially vulnerable; nor am I living in my parents' home, institutionalized, or have any children in the household. So in those respects for this survey, I'm atypical.
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Aside: https://www.pewresearch.org/fact-tank/2017/10/11/the-share-o... is an earlier reporting of the data based on the 2007 - 2017 data.