[kbanman]

Hootsuite also started as an agency side project, and I'm sure there are more.

Intentionally following this model doesn't seem sensible though; with VC money so accessible if you have already put together a good team you might as well focus on the product itself. Agency work is not fun.

[Brendinooo]

VC money takes time to get, it requires you to give up some part of ownership/control, and puts pressure on you to be a unicorn.

Fine for some; certainly not foolish to go a different route. Basecamp never wanted to be huge, just successful. I'm working on a project that our company funds through agency work, and it's fine.