Unless you play poker for a living, or at least for a significant portion of your income, I don’t think you should think in terms of bankroll requirements. To paraphrase the wisdom of Donald Rumsfeld, you go to play with the bankroll you have, not the bankroll you might want or wish to have at a later time. Sure, you can go ahead and calculate the number that would give you a 99% chance to avoid ruin… but is that number really meaningful to you and your lifestyle?
Unless you rely on income from poker to pay your bills, you’re playing as a hobby. If your hobby were photography, would you be asking about your bankroll? “Hrmm, I can sell X photos for Y dollars per month, plus or minus, and spend Z per month on equipment and supplies… what dollar figure D ensures that I’m likely to stay above water with 99% chance if I hit a bad rough patch and don’t sell enough photos for a few months.”
Kinda silly, right? Most people would say, “I enjoy photography, and I’m willing to spend $500 per month on it.” Out of that budget comes investments in new equipment, film, ink, etc. If you happen to sell some photos for some extra cash, then great. If you happened to sell a ton of photos all of a sudden, maybe you would increase your budget to $1,000 per month. If I told you that, at the rate you were selling photos and buying equipment and supplies, you could expect with 95% certainty that $127,350 would be a self-sustaining amount of cash for your photographic lifetime, what would you do. Would you do anything? If you’re like most people, you’d react to that news with a, “Huh, really? Interesting.” And then you’d be back to your $500/month budget.