OP, as the others have said, "you missed out on a good opportunity" sounds like something people say when they have no clue how relationships with other people work. It also sounds a bit like a childish backlash against perceived rejection. What's worse is that you felt this petty nonsense was worth bringing here, so you've taken time from people you don't even know for absolutely nothing.
People have lives and just because you text them, doesn't mean that they should feel obligated to respond quickly. Unless it is an emergency, don't put time limits on how quickly you think it should take to receive a reply. This is my favorite part "you missed out on a good opportunity and im sorry for you" Damn, you are full of yourself aren't you. I mean I thought I was conceited, but you've got me beat! No, YOU missed out because you were to scared to respond when he asked you out. He has moved on, so exactly what did he miss out on? Oh, wait he is missing out on something...you overthinking a simple reply. I cannot tell you how many times I auto reply to someone with a "miss you too" or some other response because they said it first. It seems rude when someone says "Miss you" to not respond at all. Why would he text you back? He is talking to someone else now....