With a 60% win rate and a 100 game sample the variance calculator showed me a loss of over 30 buy ins. I find this extraordinary! Even for a very solid 60% winner a downswing of this magnitutude is still possible! Let alone those with lower winrates.
Although most bankroll guides suggest around 30 buyins, I now see this as very risky. Even if you moved down after losing 10 buyins, then lost another 20 on the next lowest level (say moving to $5 from $10) that would still equate to losing 2/3 of an original 30 buyin roll.
People truly underestimate variance. Everyone should be aware of this. My current bankroll plan was 40 buy ins, which I felt was adequate. Now I am going to increase this to 50 buyins for the $20, 60 for $30, and even more for higher stakes, so to reduce my chances of having to move down a level.
Thany you for the variance calc husng.com
Downswings can be worse than that, as most 60% winners are probably not used to massive swings and are less experience (lower stakes, can't win at 60% in high stakes really). Therefore, emotion and worsening play will often set in, thereby lowering their actual winrate and exposing them to even more negative variance.
However, it's important to keep in mind that most sane, well minded players will move down before they ever reach 30-50 buyin downswings, meaning playing on a 30 buyin roll can be almost completely safe. Even if you drop 10-15 buyins, move down and drop another 10-15 buyins, you still have around 40% of your roll left and you'll be playing two levels lower. It could just be variance, but it's almost always best to just work on improving your own decision making. As long as you don't play recklessly with your bankroll, you shouldn't have to constantly worry about anything other than your decision making. This is good, because your decision making is directly related to your edge.