It doesn't shrink as much.

Mainly the result of societal pressure or expectations. Being a 33 year-old man, never married. That's "normal". If I were a woman, people would be asking me when I was going to get married and have kids (very much depends on area, but this is not at all uncommon). As a 33 year-old man, it's also not thought of as strange for me to date women in their early-to-mid 20s. The same is not true for women my age.

Then there's also just how people tend to rate attractiveness, which is something that really matters in a lot of these online dating systems. Men are generally viewed as (physically) attractive at higher ages than women are. A few wrinkles on a guy, some gray. That makes him "distinguished". You don't here people saying that about women as often.

The age range and feature-sets for what makes women attractive (again, this is emphasizing first impression attraction) are much narrower than for men.

I suspect that men are simply judged on a wider feature set than women. women prefer younger men if judging on aesthetics alone (full head of hair, abdominal definition, clear skin), but place a lower priority on attractiveness and will tolerate signals of aging in men if they are accompanied by signals of wealth/cultivation/accomplishment. Men who are unaccomplished/uninteresting and also older will experience 'pool shrinkage' at a similar rate to women.

"Being a 33 year-old man, never married. That's "normal". "

My experience was different. I was called a loser by more women than I could count because I wasn't ever married by then or had kids.

Where is that? I'm in the US for what it's worth and my particular experience is in the southeast.

Mostly in the SF Bay Area, of all places. I moved to north Texas and while it still happens, it happens way less often. But the Tinder landscape is definitely different.

Men's peak attractiveness is at 38. You aren't too far off it.

Only if you're lazy. If you improve yourself (gym, career, hobbies) your pool should only grow as a man into his 40s.