You are very correct OP, it is not limited yo trading but to every form of investment, always ensure you invest an amount you are able to bear its loss, do not borrow to trade or invest and always trade with core knowledge and emotional balance
This is a valuable lesson, 10BTC too expensive, many people will be stressed. You are right, we need to determine exactly how much we can lose, it is very important to help us not lose confidence in our investment plans.