If someone's book is going to end up being read by people, and if those people gain something from reading it then I think it is your obligation to write it. It would be a travesty for knowledge not to be passed on.
Did you know that we, in the year 2005, have the same mental capacity as cavemen had?
This means, that the only difference between us and the cave men is our ability to store knowledge. Not only store it but transfer it and communicate it from generation to generation. I think it would be a crying shame if someone such as yourself, who obviously has something to contribute (otherwise it would not have been suggested to you and all the replies you are getting would have come to be), does not add to the pool of knowledge that differentiates us from animals.
This may seem a bit idealistic and pretentious, but I truly believe in the notion that knowledge is for sharing, and above anything else rewarding!
If you need more reasons, then tell me and I will list them alphabetically!
Its meant to be!