Why are guys like this?

Ok screenshot isn’t mine but I swear dudes like this all radiate the same energy. My recent ex would do something similar and I truly can’t figure out why. I’m posting the screenshot cause I deleted all my texts and this is spot on. I’m trying to make note of the red flags to look out for. So why do they do this? Insecurity? If so then what are they insecure about that theyre not good enough for you? Do they only have the intent to hurt you because deep down they’re hurt? Or are they just cruel and mean???