Why am I never good enoguh? Why do stranger coworkers feel comfortable criticizing me?

there's many guys at my job who feel comfortable telling me what to cange about myself. One guy said i talk too slow and pause too much and he wouldn't wanna date a girl who did that cause she's weird.

Another guy heard me call another guy "bro" and asked why i called him that and said that its better to call men "sir"...

Other guys ganged up on me one day and said i should dress sexy and get my hair done wear makeup and stuff like that. One said someone might ask me out if i came to work in braids one day.

My question boils down to why am i never good enough for people? I try to be very nice and i dont want to criticize others because i think its very rude. Yet with how nice and polite i am, its never enough for anyone. Its like nothing i am or anything i do is not enough.
Why am I never good enoguh? Why do stranger coworkers feel comfortable criticizing me?
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