As the OP of a thread that went on for 5 pages on this very subject, I would just like to point out that for some people (like myself who have been slowly plugging away at CSEL for the last two years) the thought of spending $3K-$4K for a CFI is where some of the hesitation comes in. At least for myself anyway. I am perfectly aware of the fact that there is no better way to build airmanship, time, etc... than instructing.
My point being that before we start posting threads flaming people who don't want to instruct for various reasons, lets remember that:
1. If someone feels like they won't be a good instructor, this feeling is valid and should be considered. I would hate to be the student of an instructor who lacks confidence in their ability to impart information that I spend $150.00+/hr to bumble around the practice area and not learn anything. Conversely, the instructor who is such a hot shot and it only "building time to make it to the majors" without so much of an iota of professionalism, care or concern in me, his current student presently occupying the right seat with him would also frustrate me incredibly. TL;DR: If I wanted to pay $150/hr to be frustrated and not learn anything I probably shouldn't be at the controls of an airplane.
2. If someone doesn't want to instruct, this is a valid feeling. You don't know why they don't want to instruct, just that they don't flaming an individual for a choice/opinion they hold without all the information doesn't make you better than them. In fact, my assumption would be (if we're judging books by their cover) is that you (and I mean generally, not referring to anyone specifically.) very well may be the kind of person who hops into an airplane without any level of fore thought because, "it's all good, I got this."
3. Instructing is a corner stone in our industry in terms of developing airmanship. However, it's not the only way. If you can get there without instructing, more power to ya.
/rant.