Co-workers these days

Why is it that for these past 3 years that i have been working i always have co-workers that want to test my nervesand tries to question every little thing you do? You know how there's always that ONE person, who just has to be the kiss-ass, in in the back of your mind you figure it might be worth it to get fired if you can just take one hit at them. I'm just ranting, but i'm tired of not being respected at my job, they lucky the economy is down the toilet! People are ruthless, do whatever they can to be above you. shamful.