need to have the costs of living expenses covered for a period of time.
Yes, very underrated aspect. At this point I could probably afford a home while also growing by bankroll, but starting out, there was no way I could have made it with poker if I had to pay rent. My total win after the first 100 sessions was... (checks) ... 4500€. I don't pay a lot for food etc., but there are still some minor expenses, so probably real win was slightly above 4000€, which means about 40€ per session, and I didn't play every day.
... and speaking perfectly honestly, this is probably an unusually good result as well, I think it's pretty common for professional players to be down after their first 100 sessions. I had some beginner luck for sure, and probably learned faster than most, also I started just playing short-stacked for months.
So yeah, no way this would have worked out if you start with normal expenses. You either need to live very cheap or start with enough of a buffer to get over the initial hurdle. You should probably plan to play for around 0 for the first 6 months, at least.