It's not a "mindset" to notice that people only reach out to you when they want something. You notice that they reach out to others who aren't you and don't include you, They reserve you for favors only. If you find out about something and ask to be included they'll say "sure," but it doesn't feel great to feel like you have to beg.

That's not a "mindset," dude.

It's really hard to try to make that relationship more reciprocal and it really sours you on trying to create other relationships. You wonder if there's something inherently wrong with you. If your lot in life is always to be an outsider.

There's also the second type of person one can get caught up with, the narcissist. They think that the world owes them everything and they will take, take, take and never give anything. This one is a typically bit easier to deal with and do a little less damage to your mental health. Though they can sometimes be charismatic, so difficult to spot early if you aren't used to dealing with that type of person. The charismatic ones don't demand anything, especially not right off the bad. They make you feel like it's your choice to do them favors.

It's easier to notice if you have exceptionally "wanty" people in your life. But can happen regardless.

Some relationships are dysfunctional. Some people are toxic. That's not a "mindset" problem. It's clear you're not familiar with dysfunctional relationships, which is great, so don't accuse others of having the wrong "mindset" when you don't know.