If you have a choice of say working full-time on your startup for 6-9 months, or freelancing on the side for 10-20 hours/week in order for you to stretch your runway to 18 months which would you prefer?
Let’s also assume that you currently haven’t launched your application and as a result don’t have any paying customers as of yet either (in case it matters).
Context switching is always a problem, and you then also have a fall-back and might get to comfortable and that sense of urgency might work against you.