No, I don't call you immature because of that, but simply on the fact that sometimes things get way out of your control. Friends move away to other cities and countries, death of parents and relatives, hell even your friends and partners die as you get older.
You are 21, not 61 (or older). We won't be here discussing this issue in ten, twenty or fourty years from now. You have no clue where you will be. I hope the best for you, but sometimes the lack of empathy towards other people will come back at you like a boomerang.

spill the tea

yes. if i see an old person eating alone in a restaurant my heart breaks a little...

Apathy is not a good look so don't wear it like a badge of honor.

And don't be arrogant. You don't know where you'll be when you're 70. You don't even know whether you''ll reach 70. Some of your friends will get married and move on, some friends simply move. You partner could die or divorce you. You can grow apart and have nothing in common anymore. Your parents will most likely die before you. Your siblings might die before you. Your cousins might not stay in touch. And it seems like more and more people are putting their folks in a retirement home and only visit them once every few months, so I wouldn't count on your kids too much. They might consider you a burden. The older you get the less people are around you.

You might be willing to work on the relationships with the people close to you, but maybe they're not as invested as you are.

Yes, it really makes me sad. It also makes my opinions about life negative