Why do I hate myself so much?

I wish I understood where this notion stems from. But I just hate myself like a lot. I feel like I go out of my way and put myself in situations to help people directly only to feel empty and manipulated alone or desperate. Build nuclear submarines for a living as a structural x-ray welder. I've been doing that for 5 years. At first I thought maybe doing something bigger than myself would help me get away from this notion that I'm a piece of s*** worthless yada yada. But if anything it's only furthered my alienation and isolation especially here in Rhode Island where I really don't have any friends. I just feel like people look at me as like subhuman or dirty blue collar scum I don't know. I know it's me reading into things too much and my overall low self-esteem in general reflecting on him myself, but it's something I really need to start making progress to improve because in 8 months I'm going to be a dad