I was thinking more along the lines of solo-founders. Obviously if you can afford to pay employees, you can afford a 401k. Which brings me back to the fact that you probably still need money to pay employees; which generally means you still need funding unless you're profitable very early on.

We're entirely bootstrapped, but we provide a recurring service and it's taken me 2 years to hire our first employee. I don't think most companies can wait 2 years after launching to hire an employee (We couldn't even.. I had to bring in short-term help on numerous occasions).