Human Nature cannot be altered...

No matter how well you think you can judge character...you can't. The best way to do so - and I am not talking about judging people just how to be able to tell character from good or bad - is to know people, know how they work, what drives them so on so forth and when it comes down to certain things, every single person is the same but in their own respective ways because character can be falsified...can be an act...human nature...is human nature and it can not be altered in any way, no matter how hard you try.
so by knowing people....it can help you go along way...

How can people act so false?
Fear…
Fear of the bad things that can happen in life. Fear of those things that can hurt us, hurt our spirit which is why people put up walls and are on such high alert and never letting their guard down.

People put up false walls though - why?

People don't want you to know the truth about them because it makes them

feel vulnerable

They are doing to others what they don’t want to happen to them and it's not so much hurting others than it is looking out for oneself which brings me back to human nature...
people will always pick what they feel is better for them HOWEVER, and listen - however...
realizing the difference between what's

best for yourself in the short run in comparison to what's best for yourself in the long run are two different things many people get mixed up

Perfect example...think how many times you've seen breakups, where the one person doing the breaking up was so sure that the relationship was bad, and that the other person was not good enough for them only to see that same person, say for example 6 months later, begging for another chance because they didn't know how good they had it to begin with

Looking ahead to the future, worrying about what will happen tomorrow and knowing that's better for you in the long run as opposed to the short run are TWO COMPLETELY different things that people have to keep in mind.