I was 30 almost 20 years ago
You know, it's crazy, when I was in my 20s I'd hear guys in their 60s refer to a 30 yr old by the term "kid" and I'd think to myself "look at this old fart trying to maintain some semblance of hierarchy/dominance over another grown man because he ain't got the juice no more

"
You hear it a lot in law enforcement too. 50 something year old cop referring to the 30something year old hotshot cop as "the kid".
Older sports coaches referring to younger coaches. They always use "kid".
And it wasn't until now, well over a decade past that age of 30, that I see it has nothing to do with trying to "pull rank" or be disrespectful or discredit the 30 year old's manhood.
It's merely the enlightenment that age affords you, that shows you that in the grand scheme of things, a 30 year old IS in fact, still somewhat of a kid. And by "Kid" I don't mean that they are "child-like"- moreso they just still have soo much more to learn and experience! They still have so much LIFE in them. So much youthful vigor!
And at 30, you still have that natural born, youthful ability to dream, coursing through your veins(you lose that!).
And here I am, not even 50 yet and it feels that way when I see a 30 year old.
Enjoy still being a "kid" man, and don't let anyone tell you that you're "old".
You'll hear it a lot from 20 somethings, but they don't know any better yet.
And you'll hear "kid" every now and then from guys 20 years older than you, but it's because they DO know better.
Just soak up every second of it in joyfulness and appreciation, from the young and the old. For you are in the sweet spot, my friend.
Enjoy the born day!