I believe these cases are not statistically dependent from each other. The things you experience have an effect on your personality after all.
I was picked on when I was in elementary school because I had a bowlcut hair. I don't believe I had any issues with my personality at that point, I remember being very nice. The bullying got harsher and continued until the 2nd year of highschool, changing its reasons, They called me nerd, weirdo, fat, glitterboy respectively throughout the years.
This obviously had effects on my personality, for example being isolated from the culture and the environment the others grew up in ( plus my soykafty parents didn't allow me to have internet when the mmorpgs and the messengers boomed ) I didn't acqiure any kind of music/film/ and other music taste remotely similar to my peers. I was honestly weird and had nothing in common to talk about when it was the last year of the middle school (I was 13-14). Causality of bullying shifted once it had its effects, now I was actually problematic.
I believe the bullying had a strong influence in my sexual orientation as a gay person. It also rendered me into an asshole that fluctuates between self-hate/gratification while being condescending towards everyone below him in some skill, and unhealthily jealous of the above, because the bullying made me an harsh critic of myself and eventually everyone after it stopped. I lack empathy towards people because they have never shown it to me.>>301>>302
OP, I also think that the friends of convienience thing is real. The most visible examples were my highschool friends who were once my bullies. I still hung out with them, but never contacted them once I graduated. College, I think, is the same, I thought I was close to some people but they have betrayed my trust.
But you know what, friends of convenience are okay too. You can still hang out together, play games, and watch movies. You can still bitch about that exam, gossip about X, discuss the latest episode of the series you both watch, go out to drink. Just don't trust them with anything and know they'll be gone once you change your environment ( this sometimes is a good thing ).
And how harsh the current situation is, most likely it will get better, or manageable, or both. You will eventually meet people like you, and even they are friends of convenience, it will be okay. They will be much better than the past no matter what.