Forget 3 months, the rule of thumb is 6 months for an emergency fund
Basically quit your day job only if your side hustle is already making more money per month (not per hour) because odds are even making more per month is still going to result in not being able to survive much past 57.
Side note, how many 57 year old indie game devs are there?
The average American doesn't do what is "conventional wisdom".