This was the last and probably most enthusiastic presentation. It was really good fun watching David's talk.
Fuck the real world
A lot of ideas "will not work" in the real world — or at least most of the people will tell you that they won't.
On of David's example was that a few years ago Java and PHP dominated the market for web application development and "in the real world" out wouldn't work challenging them. Despite that, he wrote Ruby on Rails anyway and it was a huge success.
Too simple
Often people will say that it's not worth implementing seemingly trivial tools. David's counter-example are the 37signals applications which are dead simple. And in fact a lot of people have simple problems and appreciate simple solutions to them.
Another example was the camcorder. This "problem" seems to be solved for years and it seems to be impossible to challenge the big players with years of experience in that area. Until tiny cameras with nothing more than a USB port conquered the world and were sold millions of times.
No plans
You need good plans to get things done and working.
Wrong! You cannot predict the future. Plans are often obsolete very early and rarely ever work out. 37signals products are very successful without any business plan.
Say no
"No we're not going to implement your feature request".
Yes, you should listen do your customers, but you need to be able to say "No!". Otherwise you not only spend much more time and money but also risk to lose the focus of your product.
All rock stars
To have a successful company you need to hire rock stars.
That's not the case according to David. There are no rock stars! What counts is a rock star environment, where everyone can live up to their potential. Trust your employees, give them responsibility, they are not stupid!
Easy domain
Simple tools are too simple to imitate and it's likely that a big company will copy it and win the battle because of their enormous resources.
In fact, easy tools are not necessarily easy to develop. Simplicity is very hard to achieve. Even the biggest companies often have a hard time challenging a well done, simple product.
Pitch the killer idea
It's all about the idea!
No, it's not. Successful businesses are much more than just an idea.
An idea is so small part of a business that it's almost a rounding error.
David Heinemeier Hansson