There’s living paycheck to paycheck and then there’s giving oneself the opportunity to play optimal while trying to grind out a living.
15 years ago, the general consciences in the circles I was involved in felt you needed a 6 figure bankroll just to play optimal in $2/$5 and sitting in the occasional $5/$10 if the circumstances for doing so were correct.
Viewing bankroll management from the view of re-buys factors in the aggression level of the games you are active in. For example straddling, pre and post flop bet sizing, etc. It also anticipates how much money is going to be on the table.
Most everyone buys in for the full $300 in the weekly $1/$2 NLHE game I play in. Straddles are not uncommon, neither are double straddles. I buy-in for $250. I am not re-buying in for less than $300, ever. And I am going to re-buy back in for $400 or $500 depending on the number of re-buys already on the table.
It is a matter of simple math. In a ten player $1/$2 NLHE game, $300 max buy-in, a player who buys in for $250 is not losing much value, if any. Re-buying in for $300 instead of $500 when there is $6000, $7000 or $8000 on the table doesn't make a lot of sense.
There is a psychological component to having a large bankroll, that poker players have termed, scared money. I don't worry about my $300 buy-in when I have $20 grand at home for poker, no more than I do if I am sitting down with $850 to play $2/$5 PLO. Not having to worry about money is valuable if one is going to play optimally.
It is a little irrational to feel the need to have such a large bankroll, but in part, we are irrational creatures. How many of us have gone on a losing streak where we have blown through 30 to 60 buy-ins? Seriously.
I haven't come close, and that includes the five month period where I spent thirty to forty hours a week refining my game playing $1/$2 at the casino, yet I am guilty of not wanting to lose the comfort of having that kind of money in reserve. And I have never had to rely on poker for my livelihood!