Do you ever wonder what the point of being polite is if people are rude regardless?

No. If more people were polite, the world would be a better place. Falling to the level of people who aren't doesn't help at all.

1 Corinthians 13:5 tells us that love does not behave itself unseemly (in other words, rudely).  God wants us to be loving, like Jesus Christ. 

Being polite and being rude is part of life. One can counter each other and it does not mean one is greater than the other. One who is nice can influence someone who's rude where that someone can become nice as well in the end.

Nope, because being polite is always nicer to do.

Polite behavior can deescalate a situation. Somebody has to be the grown up.

I find it is a waste of time to be polite to liberals.  These idiots will be obnoxious, angry, insolent, and rude not matter how they are treated.

Nope. "Be the light you wanna see in the world." It humbles the heart. And another good quote, "Be kind for everyone you meet is fighting a difficult battle".

Yes, sometimes I feel this way and wonder that.