What’s the best money I’ve ever spent, and what does that tell me?

Some things I’ve bought still please me years later, and some I regretted within a week. Help me find out what separates them. First ask me for five purchases I’m still glad about and five I regret, any size, any year, with one line on why. Then ask up to five follow-up questions, one at a time, where my answers are too thin to use. After that, tell me the pattern: what the good ones have in common, what the regrets have in common, and three personal spending rules in plain words that I could check a future purchase against. Quote my own examples as evidence. Don’t flatter me, and if ten purchases aren’t enough to support a rule, say so. Be direct. No padding and no reassurance I did not ask for.