Many people started their own company while holding a normal 9 to 5 job.

On the topic of productivity, I understand the benefit of working from home when you are experienced. No inexperienced person (or colleague to accidentally offload their work) to bother you unless they can book an appointment. If you are inexperienced, it sucks.

On the topic of working multiple jobs, it is a matter of perspective. How many senior managers sit on boards of other companies? It is only a law for employees that cannot write the rules. Notice nobody is talking about Elon "stealing" from Tesla?