[Jiggly]

Being nice can result in people trying to easily take advantage of you so its also important to be assertive and don't let people walk over you
However i don't think being nice and polite is a disadvantage or means you have less value.

I think you can be nice and not let people take you for granted. Being a nice person, and being a person who needs to be validated by others, are two different things that can often get confused. As you get older in life, you notice the assholes don't always win. Sometimes they might, but the nice people are the ones everyone appreciates and respects. At least, that's what I've found in my working life. High school was very different.

If what the assholes are achieving now is bothering you, try to turn your focus inwards. Decide what YOU could be doing right now to reach your goals. Before long, you won't be as bothered by the assholes. We don't live long enough to justify spending time caring about what the idiots and nasty folks do. Control what YOU do with your life, not how they treat you.