One of top harsh lessons of reality is... being nice doesn't always work.
Yes, it helps- a lot- but there are those who find being nice foolish and even offensive, responding with contempt, mockery, and even aggression. Lucky for me I didn't learn this the hard way.
But my point is this: you can be the friendliest, most polite and courteous person alive, and while this will get you far, you will hit a brick wall if the person you're being nice dislikes you for any number of reasons. It isn't always justified, but let's face it- people tend to care more about finding people who agree with them and don't offend them than whether or not you're a nice guy.
Here's an example... say you're opening a door for a lady, and you smile and say "Good morning!" Sounds fail-safe, right? Now, let's say you wear a sleeveless shirt, and expose your many colorful and vibrant tattoos for all to see. What if the lady who you treat kindly really, really hates tattoos? She'll probably sneer at you.
Hyperbole, yes, but a lot of people are stubborn, whether they have a right to be or not. One thing I realized is that it's real easy to preach to the choir, but nigh impossible to preach to people who aren't in the choir.
If you wanna spread your message more, you're best off preaching to people who are thinking of joining the choir.