When to be selfish?

I don't like it when someone goes "Wow, you're so good at understanding others. No wonder you want to be a psychologist."
I do NOT try understanding others because I want to become a psychologist.
I try my best to be understanding because I am human.
Do we learn how to cook because we want to become a chef?
Do we learn how to drive because we want to become a driver?
They're skills which we need to learn in life.
It's the same.
Do we learn how to understand others because we want to become a psychologist?
Are psychologists the only people in the world who need to learn how to comfort, listen and care? Do the other people in the world need not know how?
Or maybe I'm wrong.
Only psychologists and those who want to be them need to know how to care.
The rest of the world can do as they want without a care for other people's feelings.
Even so, psychologists are still human.
I am still human.
I feel.
I tire.
I hurt.
I surround myself with people whom I care for with all my heart, and in return they torture my heart and mind slowly like a poison.
I let myself be conned by the hypocritical people who call me a good friend.
I'm a very kind idiot.
I get hurt over and over again, but I keep silent and wait for a chance to be there for the person, to stand for the person, to be ready to catch the person if he or she falls even though my arms are already broken beyond repair.
Why is it that there is no one who can give me what I truly want?
Why is it that there is no one who can understand me?
Because I don't say it out?
Then it isn't fair.
I care for the silent people too.
I kill my own pain for others to lean on me.
Once they have the strength to walk on their own, I am left behind.
For so long I've been silent so that others can speak.
For so long I try to remain strong for others.
'Do to others what you want them to do to you.'
I try my best and listen to others, to help them when they have problems.
Who listens to me?