There is a reason “learn to laugh at yourself” is a recurring quote from many people.
This is all this is, to learn to laugh at your younger self. No one is saying your feelings or thoughts as a teenager are invalid but perspectives and priorities change when you get older and the things that make you feel and act that way will seem trivial and therefore silly.
There is a reason this is a recurring theme between generations. Sorry but your generation is no different. It is not bullying, it is learning to look back at your younger self and see that the difficulties you were facing were relatively trivial even if they didn’t feel that way at the time.
Also please remember your sentiment the next time you see one of these memes “attacking” millennials. Basically the way you’ve formed your argument here is that this meme in this OP is “bullying” millennials.