One of the mistakes I made when I first started looking for domains was buying things that were only slightly better than or equivalent to something a person who was starting a "random" project would want. In other words, they didn't have an obvious market that could be counted on..
If someone wants a domain for their project, they will probably go to instantdomainsearch.com and yours will just be another one that happens to be registered and they'll pass on it (because they probably don't want to spend a couple hundred dollars on a domain name). But if your domain is a generic term or phrase.. or a brandable name.. in a niche where you know at least some people will be able to cough up the money, you will be better off.
For example, I wouldn't bet on someone creating a 100k charity bike ride for Multiple Sclerosis AND wanting to buy your domain when they could just register MS100k.com.