[etjossem]

It's quite common among self-funded companies in our industry to start out providing professional services, and immediately plow that money back into developing their first product. When the product starts bringing in revenue, the consulting side of the business can be safely closed.

So I'd argue that consulting on the side is bootstrapping for many founders; it's just one of the many ways to weather those first few months of product development and sales. Another way is to be independently wealthy enough to keep the lights on until the product starts selling.

Others - like YC applicants - spend time looking for outside money. There is no universally right answer for every business.