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.
Everyone makes their choices. I wonder if you will always feel that way though and I also wonder what people miss out on. For example, it is also too much trouble to cook a good meal, since survival doesn't require flavour. But what is worth "the trouble".
It is a massive problem. People are idealistic to the extreme, unable to deal with anything that doesn't meet their expectations. And since nothing will, they settle for a life less than they are worth.
That is really the question. With food, it's easy, people can just order. But in relationships, especially getting married and having children, it isn't something that you can go around or have take backs. A lot of people don't consider the rewards to be worth the risk, and I can't really blame them. For me, I think I'm deciding with the best information I have now, while still planning for the future.
I have thought about this a bit and I reckon it is perhaps worth asking people in different age groups older than us about their experiences and regrets, as well as the things they believe brought them value.
From what I've read, most older people regret what they didn't do. If they are married with kids, they would say they wanted to travel more and enjoy being single more. If they are single, they would have wanted to get married and have kids. It's basically grass being greener on the other side.