Yes, a lot of it comes down to not trying. I certainly know that when I was single and lonely (and miserable and bitter), I was just not actually doing anything to change that.

A bigger problem is that the modern world is too comfortable for the human male. There is no push factor that drives them to try. Video games and porn and weed may not be the full story, but they are cushions that soften the blow you feel when you fail to do anything. You have to have a drive, a hunger to achieve things, including achieve women, but that gets sapped along the way.