For every 37signals there are at least just as many examples of companies that set out to build a business...and built it. I can see why scratching your own itc

For every 37signals there are at least just as many examples of companies that set out to build a business...and built it. I can see why scratching your own itch may be the better way in certain situations. But I can just as easily see going all out to build a business of apps. Is there even a way to gauge which one is "better" other than personal preference?