Interesting, in the Chassidishe world boys are considered ready by 19, in some Chassidishe cirlces they even start shidduchim by 18. Most Chassidishe married men also start working at an earlier age than Yeshivishe men. Men starting shidduchim by 18-19 and working to support their families is more in line with what Chazal had in mind.
I really don’t get why Yeshivishe boys start shidduchim by 24. You don’t necessarily mature as you grow older, middos simply become more entrenched if one never worked on their middos at an earlier age. A boy or girls who is selfish by age 18 will most often be just as selfish, and sometimes even more, at age 24.