Mine is passion, my website is related to drugs and addiction because its what I want to do once I have finished my uni course in April My passion is to help as many people as possible while as a volunteer which I do now and on my website. Money for me is not really an interest as such I'd rather generate just traffic and have Adsense to help fund the website I provide to people.
What is it for you? Passion of the niche or how much money you can make?