Why does our generation age ourselves so much?

I'm a 27 year old and the vast majority the people I keep up with are in the mid and late 20s. Anyways, I'm already seeing people post memes about being in their thirties. People who don't want to do this or that cause they're too "old". Like bro, you're in your twenties lol. Girls who are literally like 3 years younger me and already think of me as an older guy lmao.

What's up with this generation?