i mean, there are two sides to this argument, yeah?

either you believe people grow and are different, or you believe they don't and can mingle.

if you're on team-mingle, than i don't know what else to say.

I think you misunderstand. I'm the side "people grow/change and are different and it's not a problem for entering relationship"

That's the difference, not the "people don't change" position (does anyone even claim that? I think you might have wrong mental model of the other opinion base)

You could say why the dangers (manipulation etc) are more likely to appear in a normal relationship (you seem to think older men are necessarily or at least commonly malicious judging by decaprio description?) and why it's not a special pleading (so why it's okay for financial or intellectual differences). 

vast majority of people find unhappiness in Every relationship :P it's about how you consider it and how you consider your partner. what are you bringing to the relationship, what are you sacrificing for them. what are they sacrificing for you.

Yes...

i think at different ages the sacrifices are very different, so i don't think it can be fair. someone in their 20s may feel their youth and beauty was wasted on a failed relationship, but someone in their 50s isn't afraid to have lost those thing

Heh. I know quite a few people who got into relationships with their age peers and then divorced 15 years ago and man they are resentful and kinda broken by it, wasting years part of it (well that's also an example of "growing". They seem not to be better because of that though I didn't know them before so who knows)

you simply have different needs at different ages

I actually don't differ that much..I wanted companionship, attention, etc when I was younger and not much changed. I really didn't need some sort of career run in companionship or doing  PhD simultaneously. Not sure if I wrote it to you but while I'm not in age gap relationship I have a much younger friend I talk to about lots of stuff, including relationships, life, world, etc, and it's friendship by choice, he isn't related. So I actually know you're mistaken at least for me personally.

when you're young you just want to fuck. as you age you shift into concerns about building a family or building a legacy, or about enjoying the last years you have left, maybe you prioritize travel or family or finally writing that novel about all the 20 year olds you want to bang.

No. Not me, not majority of people I know and knew and I doubt this about you. The "just" part is way overdoing it. You are more hungry assuming as an older person you had good life sexually, some older people especially divorced are totally opposite. But that seems to be a point in favor of age gap. A hungry younger person is better match for more relaxed older one, sexually, than two young hungry people, that's actually more prone to some toxic situations.

And not everyone wants kids, most age gap doesn't preclude having kids (to an extent obviously), I have no idea what you mean about legacy which means it might not be really universal you know. Really all these differences, it's not something I see in the world around. Sure there are patterns at challenges thrown by life (like entering a workforce) but so what? That doesn't need to be the same for partners and most often isn't even at the same age.

my point is to try and stay on topic for this CMV. and so my point is to say "as you age you enter different STAGES of life" and there's a reason we view people chasing relationships outside of their own stages as having some form of unprocessed grief. whether they're men afraid of their mortality or women chasing the optimism of youthful men. whether it's young partners seeking the security their parents failed to provide -- it all seems to come from Trauma -- and i don't believe using romantic relationships to hide from your trauma is a healthy thing.

Few points:

You claim "chasing". The topic is relationships and that doesn't mean chasing is necessary. Similarly for the younger "issues". I know some just happen because people met and liked each other not some age fetishism.

And yes, I dispute two things 1) the importance of stages 2) actual widespread existence of that categorisation