Research shows that surrounding yourself with happy/positive people increases your happiness by 10%. (Comparison: financial freedom increases happiness by 7%, pets 6%, food 4%)
On the flip side, each downbeat/negative friend in your circle can reduce your overall feelings of happiness by 8%. Studies show that happy people live longer, healthier lives and can spread their happiness 3-degrees to friend of friends.
Moral of the story ... Be Happy! and avoid Crab Asses!