I guess I am one of those people that decided to stay alone. I don't want to have kids. Having seen the baggage that can come with a partner [my mother's side has a lot of familial issues], being in a relationship is too much trouble.
Although, I am not like the ones in your example that spends everything and leaves the future up to chance. I still save and have some plans for the future. I think a big problem is social media showing us perfect relationships even though they aren't. People have become too idealistic and since they realized that it is impossible, would rather not go through it anyways.