I was in my 30's before I realized that life wasn't like I thought it should be and people didn't treat others like I thought they should. But it wasn't until I was in my 40's before I actually accepted those facts and realized I couldn't change others, but could only change myself and do the best I could to show kindness toward others.
I also realized later in life that most people only care about themselves unless you provide them with something they want either emotionally, financially, or physically, and then they only care as long as it fits their needs. Very few people will care about you because of who you are rather then what you can do for them. I realized at that time that you can not count on most people when you need them, most people will only be available when they need you. That's when I began paying more attention to people's actions rather then what they tell you about themselves.
Another thing I have learned is a person's perspective only changes when they allow themselves to grow emotionally, mentally, and spiritually. Unless we are open and willing to grow, we stay the same all our life and never become anything more, wasting all the potential we had to make a positive contribution to anyone, including ourselves.
Finally, I came to realize late in life that when you don't pay attention to the signs and messages you are being given to help guide you to a better life, you miss out on fantastic opportunities, and will always look back in regret once you realize what you have missed. Along with that realization came the painful reality that you will have to repeat some lessons over when you don't learn them correctly the first time.