Not me, but a friend of mine who was constantly bullied in school seems to be trapped in a teenaged mentality. He's 28 years old now and he reacts to many things in an immature way. Things that wouldn't stress out 99% of people stresses him out easily, such as setting up a date and place to hang out, what restaurant we should eat at, where he should park his car, etc.
He has a lot of insecurities and his view of the world and people in general sounds exactly like what a moody 17 year old loner would say. He has a great disdain of outgoing "party people" and sees them all as shallow, fake people. He loves to emphasize how he's "so introverted" and "anti-social" and "deeply artistic," calling himself a writer even though he has never completed, or even shown any of his writing to anyone.
This is just the tip of the iceberg. His love life, or lack thereof, is a whole 'nother story. He constantly falls for guys who are clearly not interested because they're straight, or just way, way out of his league. He falls in love the way a teenager falls in love: so completely that his world just shatters every time he gets rejected. That's not a bad thing in and of itself, but he falls in love with at least 3 - 4 different people in any given year. He would then post facebook statuses of Taylor Swift/Ariana Grande/Random Female Pop Star lyrics in the hopes that his crush would see it and somehow know that the status is meant as a dig to them.
He constantly complains about how heartless and immature his crushes are for not noticing how much he cares about them, even though he's only ever hung out with that person a grand total of three times, usually with other people around. He doesn't even go on one-on-one dates yet he falls in love with them!
I should also mention that when I said that he gets rejected by his crushes, I use "rejected" very, very loosely. He never admits his feelings to anyone that he's fallen in love with, so he's never actually been rejected. He falls in love, hides his feelings from them, avoids the person because it "hurts too much to see them," and then he gets bitter and angry that his feelings aren't reciprocated even though his crush wouldn't have any clue that he's interested in them.
I know it sounds like I'm just describing a pretentious douche, but all of it comes from a very immature place instead of a self-involved perspective. He's not arrogant about it or even malicious. He genuinely thinks that way and doesn't realize how silly he sounds, even though we point it out to him all the time.
It's sad because there are many times when I get impatient with him. How could I not? It's like talking to a child sometimes. He has a lot of trouble grasping simple solutions to shallow problems that he constantly stresses out about. His lack of common sense is infuriating at times and I snap at him or go too hard on him. I don't even regret it because I simply have a difficult time understanding why a 28 year old adult would actually call me on my cellphone and ask if he should "post these Taylor Swift lyrics on facebook so that my crush would hopefully realize it's about him and feel bad for hurting me so much."
There are many, many more examples of his immaturity, but I'm sure you get the picture. I really do feel bad about how the constant bullying resulted in the person that he is today. A lot of bullied kids end up growing stronger because of their difficulties, but he's simply not one of them. I think the bullying really broke him at an early age and he's never gotten over it. He sometimes talks about how much the bullying hurt him and understands that it's the reason why he has great difficulty making new friends, being open to others, etc. I know it sounds like I can't stand the guy, but he's a really close friend of mine in spite of all his annoying traits. I just do my best in being more empathetic since he deserves it.
TL;DR: Bullying sucks.