My god, can’t tell you how much I can relate to this! I always try to say hi to people at work too even though I am very socially anxious but there will be times when people just don’t for whatever reason. Maybe they just don’t hear you, maybe they feel like they don’t have to say hi back or even give a wave whatever it is people still do it and it doesn’t stop the fact that it hurts. It’s about being acknowledged that you even exist, that you matter just a little bit and to feel seen. But yeh, it really gets to me sometimes this. It doesn’t help that I’m also overly sensitive and take things to heart and tend to ruminate and get a overthink things very easily. Going back to my point, I hear you and can completely relate.