Hi guys.
i want to ask a question about friendship.
I have a lot of friends but most of them just want to take advantage of me. They only call when they need my opinion, knowledge or help for something what i am expert on.
When i first meet someone, everything is normal. After when they find out that i am expert on something(etc. school lessons, or human psyschology,..), they just hang out me for making me something for them or learning something from me.

For example: girls try to learn something about boys, want me to help them for their homework; guys want me to help them about their girlfriend or a girl that they want to pick up.

(by the way i am not letting anyone to use me)

Even i dont let them to use me, they are keeping try.
Why anyone just want to hang out with me only for spending some fun time?
What is friendship?
Why i cant connect people with a normal way?

I think you might be looking at it incorrectly. Ever think that maybe these people just want to start a conversation with you and they're trying to build rapport by talking about something you're interested in? Several of my friends know that I read a lot about female psychology (or "mind-fuck tricks" as they like to call it) and they just use that as a way to spark a conversation. Are you sure you're not just being cynical?

lead the situation, and go to school to learn better english

if you want to have fun with people, then have fun with people, don't wait for them to have fun with you, be more pro-active, life won't just come to you

people work off of their values, and most are needy in general, you are no different, these people want to be around you to obtain what they value from you, in the same way, you want to obtain value from them, basically all you are feeling is that these people are needy and want to take value from you, without giving any in return according to your value system

so, what your solution has been, is stop giving value, because you are not getting anything in return, thus both parties are needy (both just want something for nothing, the frame is all about taking instead of giving)

what is friendship? it's just two people that have rapport together and don't assosiate negative emotions towards each other,

why can't you connect with people? beats me, maybe bad english? get to know people better

why don't people want to hang out with you for fun? maybe they do not value you as a fun person, if you are not fun to be around, why would someone go looking for a fun time from you? if you are always serious and being some ''expert'' then that is how you will frame yourself and that is what you will be treated like

if you stay serious then stop delivering the only value you have to offer at all, they will just detach from you as there is no value at all for them to gain when they assosiate with you, and people all share a fear of loss, so if they only have something to lose and nothing to gain from being around you, naturally they will avoid being around you

give off more value, more fun, more info, more giving, less taking

Thank you for your answers.
Snarg i am sure i am not cynical But you are right. Some people use this way just to spark a conversation with me. And i think as pumpington says, i am delivering only one value.
Yes. I am not so fun people. That's why they just take the value that i give them and want to do nothing more with me.
I think i have to learn how to be more fun.