Midlife crisis at 31?

Any older guys have some kind of midlife crisis at 31? In the last year, my dad was diagnosed with cancer and my brother was committed to a mental institution (he's been barely functional for the last 10 or so years and it's long overdue). My mom's been dead for a long time now. My relatives don't talk to me anymore for cultural reasons, I'm the black sheep of the family because I work in entertainment and they all work professional engineering or medical jobs. My friends are all either settling into relatively non-social lifestyles with wives and kids, or preparing to move to different cities/countries. It made me realize how alone I'm about to become, which wouldn't be an issue, but I worry about taking on life all by myself with no one on my side to catch me if I fall.

At the same time, I've accomplished a lot in my life thus far. My finances and career are in great shape. I'm not lacking anything in the personal fulfillment department.

I just feel like something shifted. I'm no longer an old young guy. I'm on the cusp of becoming a young old guy. I kind of thought that after 30, I'd revert back to being in my 20s. Instead, to no one's surprise, time moved forward, and I'm 31. I feel like I'm no longer allowed to be myself or be able to do the things I used to enjoy, because I should have "aged out" so to speak. I feel immense pressure to change my life and give up the things I love because it's abnormal for someone my age to keep doing them.

When I type it out or say it out loud, I feel like I should be ashamed that I'm 31 and still going to bed at 3 AM and sleeping until 10 AM and spending every weekend going to parties and hanging with 20-something year olds. But I just don't see myself as being as old as I am. In my mind, I'm still the same college kid I was 10 years ago, I still enjoy that lifestyle, but I feel like it's repulsive because I'm supposed to be subdued and boring now.

Did anyone else feel the same way when you were in your early 30s?