Kid and kiddo insulting or endearing?

There's a lot of people who will be like "what's up, kid?", they call me "kiddo", "good luck, kid", etc. I am close to being in my mid 20s. Yeah, some of these people are friends of mine or are people I used to be close to, but I am an adult now. Why do they call me a kid? Do they look down on me? How should I read it when they call me kid or kiddo?