At the end of the day, the biggest reason for this disparity is that most women find most men unattractive. That statement begs repeating - statistically, women find the _majority_ of men to be less attractive than what they believe to be the "average" man. Look no further than the oft-cited and since-deleted OkCupid post which dug into this in great detail. [1] More contemporarily, women-centric communities like /r/FemaleDatingStrategy will happily just come out and state this as fact. [2] (warning - if you're a man who struggles with self-esteem I wouldn't recommend clicking that link, you're only going to feel worse)
The real kicker here has and always been the chart which demonstrates that women rated 80% of men as being less than average attractive. Anyone with other single friends in their 20s and 30s can attest to this; it's pretty common to hear a complaint from a woman like "there wasn't a single cute guy at that bar" or "none of my coworkers are people I'd consider dating."
I don't really know what the answer is, you can't tell people what they should or shouldn't like. Telling men to just "be more attractive" doesn't really work, and telling women to "lower your standards" is equally silly.
As I've read elsewhere on HN, the future I envision is one where a good chunk of straight men are largely just removed from the dating market. We're already beginning to see that, with 28% of men in 2018 reporting no sexual activity, with that number only likely to rise. [3]
The only advice I can give to men in that position, especially ones who don't hit the marks which serve well in OLD (tall, white, and fit) is not to beat yourselves up. Your personality probably isn't the problem, you don't "hate women", and you certainly don't just need to "shower and touch grass"; you're playing a game in which the odds are stacked against you. There are certain immutable traits which our society finds incredibly important in hetero attractiveness, and if you're lacking those traits, it's absolutely no fault of your own.
[1] https://www.gwern.net/docs/psychology/okcupid/yourlooksandyo...
[2] https://www.reddit.com/r/FemaleDatingStrategy/comments/iu5nu...
[3] https://www.washingtonpost.com/business/2019/03/29/share-ame...