Going from 0 paying customers to 1 is really difficult. Specially if you're asking for a recurring subscription.
Getting noticed is one of the hardest parts. Just having a great product is no longer enough.
For every Basecamp, there are probably tens, or even hundreds of similar competitors.
Can I name a few? Maybe.
What about the top 10? Probably not, and that's exactly the problem.
I've read several of these SaaS walkthroughs and it invariably seems to follow this pattern:
1. Author has a blog with a large following on some topic.
2. Finds niche in that topic.
3. Makes a product and pushes it via their blog.
4. "Incredibly" their product gets tons of customers.