Nice guys act nice because they hope it will improve their changes and make people like them.

When you act kindly or nice to people because you want to be nice or kind is not nice guy behaviour.

I'm writing this because I sometimes see guys hold of from saying something nice like "be careful" because they don't want to be the nice guy or act like they don't care and are high status. They're afraid it will sub communicate neediness, make it seem like they're too invested in the girl and doesn't help with their game.

It's high status/value when your aren't afraid to tell kind or nice things because you want to. Especially if what you're saying is sincere. No matter what the reaction will be