OP, it sounds like you would massively benefit from some CBT. You are displaying clear symptoms of disordered thinking (not a criticism, I used to until I had CBT and it was a real eye opener). Phrases like 'This sort of thing only ever happens to me.' And why are strangers always rude/mean to me, treat me like dirt ?etc.
Rationally you know that strangers are also sometimes very nice to you, that far, far, FAR worse things are done by strangers to people who have done nothing to deserve it, the world over, from Gaza hostages to refugees in 'camps' here in UK, and that in comparison, strangers are pretty neutral with you. But when we have confirmation bias, it's hard to accept this.
Can I recommend a really fun exercise? Buy a small notebook or open a page on your phone or your laptop and keep a record of every time a stranger is nice to you. From the cashier who smiles and says 'have a nice day' to the person who says 'after you' as you enter a shop, to the passerby who says, 'Morning!' For now, ignore the evidence to the contrary , even if there is plenty of it, and only write down evidence that proves strangers are sometimes nice.
Start doing this and something weird happens. People get nicer to you. When I kept a record, it had things in it like, cashiers giving me free bunches of my favourite flowers (by chance) and free chocolate, just because I'd had to change till queue. Or strangers saying they liked my coat or my dress. It's a really uplifting and empowering game to play with yourself.