I feel like there's a bunch of people who feel they peaked (or got preggo) in highschool that brings the average down to a range that is very uncommon. the age (and social economic status) of the population being surveyed also matters a LOT here. Same for all the stats in the picture, You really would need to see a histogram or something for all the categories to really make any conclusions, different life conditions will lead to multimodal distributions.

Or it could be an incel meme that's just completely BS.

That said 23 was a really happy time for me, last year of university, lots of freedom, very few responsibilities, surrounded by like minded individuals, full of confidence and not old enough for any long term problems to really become a problem. IDK if I would call it my most satisfying time, but it was definitely a local maxima.