It all starts with the domain and overall ease of ranking. You might have the perfect niche in mind, but if you're not able to rank for it, you're going to be spending gobs and gobs of time doing the necessary linkbuilding or social media positioning or money to buy traffic in order to get any traction. Get an exact match generic keyword com/net/org domain on the other hand and sometimes even with little content and links you can score page 1 or even #1 for the term, which can be nice if it's a high traffic and/or high CPC term.
I have a bunch of mainstream developers/SEOs who are repeat buyers of mine getting these kinds of domains from me and they're undoubtedly making a killing from developing on them. I've got over 2k domains and I'd get into it myself if I didn't hate dealing with all aspects of development. :/
That said, domaining is a mainstream biz itself and business is good.
