knowing when to stop, again
knowing when to say: that's enough for me.
it's probably one of the wisest things to learn.
Knowing your stop limits and taking actions on them will help you a lot and if you take necessary steps beforehand it will help to reduce the financial burden otherwise learning from the mistakes can be costly in gambling .
yes, there are no gambling schools so one can take it as a learning expense too, but sometimes it is just too expensive to let your emotions run the bankroll
better to use rationality and control yourself than to deal with deep regret later
unless you win out of luck, then there won't be regrets but you'll have to fix bad habits later on on the road