"It's good to learn from others, so you don't have to learn expensive lessons yourself"
I read this quote long ago, and I have been learning from others ever since

No matter how conscientious you try to be by learning from others in order to avoid pitfalls, you must still have to make your own mistakes to learn better. Like they say, "experience is the best teacher." People don't gain experience by learning from others. They've to be involved to get that. Experience comes from a firsthand involvement, not a story told or witnessed.
I don't think it's always necessary for you to go through experiences to learn — as mentioned in op, knowing what gambling did to others, I saved myself from repeating the same mistakes. Though, I do accept that making mistakes is unavoidable part of life, but still the more learned without going through expensive lessons yourself, the better.
"It's good to learn from others, so you don't have to learn expensive lessons yourself"
That's true. Although some lessons have to be experienced to be learned, avoiding silly mistakes can go a long way. Learning from others would mean reaching out to/ reading from true crimes and confessions althrough the period of the horrible experiences they've had.
I don't deliberately seek things to learn from, it just happens as life goes on.
I know people irl who destroyed themselves/their families by gambling activities, there is this story of Mahabharta [1] where king Yudhisthira was led to ruins by gambling — so what saved you from doing stupid in gambling?
I haven't read about the story from the link below, but the self-awareness on matters that concerns bad decision in gambling was enough to put me in my place. I don't gamble what I can't afford to lose.
I think reading summary (which is mentioned in op) is enough
