When I was the PR manager for a college radio station at a small school I learned I had to spent $30 on photocopying to promote a dance by saturating everything with posters. A lot of people who want to get rich without working in marketing would want to spend more like 30 cents and give you all sorts of excuses about how the people who really want to go to the dance will seek out of one the 6 posters they put up.
When I took over PR for the radio station our dances were poorly attended and had a reputation of being poorly attended so nobody went.
After a few years of investment people knew a KTEK dance was going to be big. It really helped that we had some great DJs too. Once you have a big reputation you don't have to work so hard.
It particularly turns up with blogging, where a successful blog is going to have people racing to post a new submission to HN and the submission will get 600 upvotes, but it often takes years of writing and promoting to get to that point.
A few personal projects have failed because of this.