What kind of insanely high growth business is going to either generate enough revenue for a Sr. Dev's full yearly salary (or close to it) or lead to investment in just a few months?
Even if you're an insanely well connected person it's going to take more than a few months to put together a pitch deck and a POC for a new business and then raise enough money to pay yourself and a few other people.
Realistically, if you're starting a startup and not currently working, plan on having at least 12 months of expenses saved (not a few months).