And when we watch other people's mistakes
It is best when we do research and learn from advice, lessons of others. It's not good to lose money just to get lesson which we learn from.
It is terrible if we only have lesson to learn after losing all of our capital. If we fall into such cases, it is only because we are close-minded and don't listen to advice of others and think we are smarter than them then we will be safe without learning their advice.
Your advice in this topic can be expanded to as Never use a same password on multiple platforms, multiple exchanges or multiple wallets.