A lot of women get butthurt when men say this and take it as Red Pill cope or something, however, there's actually a decent amount of evidence that this is the case. Even society as a whole seems to believe this too even if it's not openly admitted.

Take for instance the men selected for the sexiest man alive covers. Notice how almost all the men are in their 30's to 50's. These men didn't select themselves, so clearly there was some consensus that these older men like George Clooney or Patrick Dempsey were deserving of the title.

https://people.com/celebrity/all-the-sexiest-man-alive-covers/

Second, look at the professional male weight lifter numbers throughout their career. Almost all of them hit their max lifting weight in their mid 30's. There strength hits it's peak in their 30's, not 20's.

https://pubmed.ncbi.nlm.nih.gov/30958059/?utm_source=chatgpt.com

https://www.researchgate.net/publication/331865241_Peak_Age_and_Performance_Progression_in_World-Class_Weightlifting_and_Powerlifting_Athletes

Prime in the context I'm using it is a combination of physical attributes and also attributes that would make a guy more attractive to the opposite sex. The reason I think older men tend to hit their prime later in these aspects is because a lot of things that make men desirable take time usually. Some guys have it all together younger but I'd say the majority don't and mature into it. It's not just looks but strength, confidence, charisma, style, leadership, wisdom, etc. At least half the items I listed most guys don't really hit their stride on till around age 30 or later.

But here's the thing, a prime always ends, whether you're a man or woman. Believing that a man's prime hits later doesn't mean I'm insinuating they'll stay in their prime indefinitely. I just think that based on the evidence presented, most guys hit prime desirability to the widest range of women in their 30's or later.