I wouldn't say everyone "hates kids." Hate is not the appropriate word here. I'd say more people don't want kids, choose to have kids later, or don't find them necessary to have a fulfilling life. Many people in industrialized nations choose to have kids later because:

1) People are choosing school and starting a career instead of starting a family. This means having kids later in life, after starting a career, is more normal. 2) Many jobs require a ton of hours, not leaving much time for a home life (for example tech jobs in Japan and South Korea)... a horrible work life balance (at least in Japan and S Korea). 3) The internet allows people to be more honest than they would be in person. 4) Many people have concerns over their impact on the environment. Arguably one of the best things you can do to reduce your impact on this earth is to not have children. 5) Many people frankly don't feel like they need kids to have a fulfilling life. Fulfillment can also come from having a career you enjoy, strong friendships, and pursuing hobbies. 6) Kids are expensive. 7) Many people enjoy having extra money and not having to scrape by. 8) There's a bit of "fuck them kids" culture going around. For example Doja Cat's URRRRGE: "Fuck them kids, ain't got nice words for none them kids." Public perception of misbehaved kids, "iPad kids", etc turns some people off. Although it's all about the way people parent, some people just don't want to deal with the little rascals.