imo, if you're serious about sim racing, then you will eventually find LFS. and then once you've found it, you'd want to support the developers by purchasing their project and further increase your sim experience.
yes there's people who are serious about LFS and have played the demo for years but break that down and put it into some kind of perspective. lets say player "A" has been playing the demo for 2 years. during those two years, he could have saved 25pence per week and he'd have the money for the full content. now do you think that player "A" should then come onto the forum and ask for more content? do you think that 25p per week is an affordable ammount to save every week?
if you look at how many people have S2 license status, you'll see that LFS has been doing just fine with word of mouth and promotions.
the way i see it, if you have not bought the product after about 6 months testing the demo, then maybe you have no intention in buying the product and so the demo should not be for you.
remember, the demo is only designed to give you an insight into what LFS S2 is all about. if it isn't enough to wet your appetite, then as the user, you should look at a different product that will satisfy your interests. long time demo users confuse me. they have already shown their interest in the game by playing the demo for years rather than weeks or months. this is the bit that confusses me. they don't take the next step and purchase the full content and make use of LFS in its full glory.