Of course ‘painfully’ is subjective, but the point is that almost all bootstrapped startups take longer to rampup than you’d like as a founder. That means a year or three of living in two worlds and juggling bill paying work with growing that side project.
The absolute best way to grow a side project into something big enough to sustain you is to have realistic expectations. A big dramatic switch from a 9-to-5 to a side project almost never happens overnight.
On a related note, it’s useful to remember that having something grow too fast means you’re going to be spending a lot of time playing catchup. So slow and steady isn’t always a bad thing as long as you’re ready for it.