Why is it that when one ask a question, their point is reduce by 5?

Rules of the game. If you return to your question AFTER 4 hours but BEFORE 4 days, and pick a Best Answer, you get BACK 3 points, though.

Check this link: http://answers.yahoo.com/info/scoring_system;_ylt=...

for all the information about scoring, points and levels. You can return to that page by clicking the blue # link next to your points or level by your avatar. Also:

http://help.yahoo.com/l/us/yahoo/answers/

which is the blue HELP link at the top right of this page has a lot of answers and instructions for you.

If you loose points every time you ask a question, you have to gain the points back by answering questions. If you didn't loose points, no one would have a motivation to answer other peoples questions.

It's the way the site works but you get 3 points back for resolving a question

That's what a question "costs" you. But you make points answering other people's questions too. It's give and take. :)

its to prevent people from asking too many questions

Because that's how life is....you pay for a service...and get paid to do it!!

this is how it is i think because there is a score thing and you gain but you also loose