The thing my grandfather taught me was that you live with all of your decisions for the rest of your life. When you make decisions which put other people at risk, you take on the risk that you are going to make someones life harder, possibly much harder. What is perhaps even more important is that no amount of "I'm so sorry I did that ..." will ever undo it. Sometimes its little things, like taking the last serving because you thought everyone had eaten, sometimes its big things like deciding that home is close enough that and you're sober enough to get there safely. They are all decisions we make every day. And as I've gotten older the weight of ones I wish I had made differently doesn't get any lighter. You can lie to yourself about your choices, rationalize them, but that doesn't change them either.
I didn't understand any of that when I was younger.
Unfortunately, some people never come to understand that. Being able to recognize consequences before acting (and changing behavior as a result) is, IMO, the definition of wisdom.
I didn't understand any of that when I was younger.