How come nobody answers about why people in their 20s don't join social groups?

[Greenson]

I am in my 20s every group I join all I see in the group are just older people and I see no one in their 20s there and when I join other groups it is still the same thing with people in their 50s and 60s and nobody in their 20s there. It seems people in their 20s don't join any social groups. Why don't people in their 20s don't any social groups?

I have got no friends and I also don't have a girlfriend. I never do meet people my own age.