If you are nice to others, people will be nice to you. That's common sense. But sometimes being overly nice isn't always the best policy -- we can attract the wrong kinds of people by being nice all the time.
Photo by Liza
Quora responders wrestled with the disadvantages of being too nice. Commenter Borang Touch explains that you need to set boundaries. You can't be nice to everyone in every situation:
you will start to attract needy, whiny, overly emotional, demanding/controlling, 'guilt tripping you if you don't do something for them' types of people.
Being too nice really is a thing and some people might see you as a pushover. Hit the link for other ways being nice can hurt you.