Most people are content with their lives. It’s not unreasonable for someone who has a satisfying life to believe that their children will also have satisfying lives.

"Despite modest ups and downs, Americans’ personal satisfaction is relatively stable, at least in comparison to the significant fluctuation in national satisfaction. The range of personal satisfaction over the 62 times Gallup has measured it since 1979 is 17 points -- from a low of 73% in July 1979 to a high of 90% in January 2020. Before this year, personal satisfaction had been below 80% only 14 times (out of the 62 measures), seven of which came between 1979 and 1984." -Gallup

Maybe you think that most people are fools and dupes, and that they actually aren't as happy as they think they are. But it's not cruel to have children if you expect them to have satisfying lives. And it's not irrational to expect their lives to be satisfying if yours has been satisfying. If you expect to transmit the mindset and lifestyle that makes your life worthwhile to your children, it's highly likely that their experience will echo yours.

Obviously you can call 4/5 people dupes and fools, but if you're an outlier, it would be foolish not to question whether maybe it's actually your your thinking that is maladjusted, not the thinking of the normie majority.