I am not sure many people don't want to focus. Some of us simply can't because they need to feed their families. Thus, the question for me at least, is not if I want to focus, but when. When can my side hustle generate enough income so that I can stop having a day job? The other option is to get external funding, which has its own set of problems.

By the way, many businesses have been built like that. Take Nike, for example. Phil Knight, the founder, worked as an accountant during the day for many years while building his shoe empire.