For one thing, "nice" has a very high correlation with "gullible" in most people's minds. Prepare for a deluge of insanely unreasonable demands and suggestions brought to you by morons who think that you're a sheep waiting to be fleeced.

Also, the fact that you don't spend every second shoving your opinion down other people's throats apparently means that you don't have one, so brace yourself for a lifetime of ridiculous and unsolicited advice from know-nothing blowhards.

Now consider the ethical side of being nice: keeping your word, treating people as you'd want to be treated, giving people the benefit of the doubt and so forth. Did you ever stop to think about the fact that being the most trustworthy person in all of your dealings basically means that you are guaranteed to be the one who gets screwed over and/or betrayed the course of your daily relationships? Dealing with less scrupulous people just ups your chances of being stabbed in the back, and hey, 99% of your world is less scrupulous, isn't it? Heh. Good luck with that.

Oh, and don't come away thinking that your pious life is some sort of exemplar to others. Jerks don't feel remorse and weasels aren't big on introspection.

Basically, you're a lot better off avoiding niceness like the plague.

</unsolicited advice from...>