Berkshire Hathaway held their annual bash in Omaha a few weeks ago, as delightfully reported by Laura Rittenhouse.

As happens at that time of year, Buffet and his even-more-quotable-if-that’s-possible partner in investing, Charlie Munger, make themselves available to be interviewed. Which is where I first heard their rundown of the seven deadly sins.

Buffet: As an investor, you get something out of all the deadly sins—except for envy. Being envious of someone else is pretty stupid. Wishing them badly, or wishing you did as well as they did—all it does is ruin your day. Doesn’t hurt them at all, and there’s zero upside to it.

If you’re going to pick a sin, go with something like lust or gluttony. That way at least you’ll have something to remember the weekend for.

This isn’t just good homespun Buffet humor. It’s deeply meaningful on at least three levels.

Why Envy Is Bad For Your Investments

First of all, you can make a case that envy actually destroys your investment portfolio. Turns out Buffet and Munger have used this standup routine before, and it was brilliantly detailed five years ago in a blogpost by Sanjay Bakshi.

Basically, if you’re really knowledgeable about a business in which you can get a 19% return, but have heard about some other business in which you can get a 21% return, you’d be stupid to forsake the 19%. Which is why good investors say things like “stick with what you know.” (Buffet himself goes into more detail in his Chairman’s letter of 1993, in the section on equity investments, even quoting Mae West).

Envy, in other words, can hurt you financially.

Why Envy is Bad for Your Relationships

Buffet aside, envy and its kissing cousin resentment are equally culpable in the softer realm. Like customer relationships. Here’s why.

If you’re envious of a customer—of anyone, really–it poisons your relationships with that person. What are you envious of? Their money? Their status? Their social ease? Their romantic partner?

Regardless of the object of your envy, your level of envy is likely to be most acute when you’re with the envied person—and particularly if the money, status, social ease or romantic partner are in play or close at hand.

In those cases, our envy oozes out of us in the most dishonest ways. We sneak furtive glances, make snide comments, look for favor, disparage the things we covet, and subtlely beg. All the while, of course, maintaining plausible deniability about what we are doing. Or so we think.

In fact, we kid only ourselves. The customer may not follow every twisted inward thought we have (why would they want to?) but they know the result. We are absent; we are not genuinely focused on them; we are obsessed by our own needs, and cannot focus on theirs.

Envy can hurt your commercial relationships.

Why Envy is Bad for Your Own Self

As if it weren’t enough that envy hurts us financially and commercially, it rots us as people too. Envy, festering, becomes resentment. The Latinate derivation of resentment is re-feeling. Feeling after the fact, revisiting the past, dwelling negatively on history—the one thing over which we have precisely no control.

Resentment is akin to playing God, groveling in the fiction that we can alter the reality of time past. It’s no accident that the 12-step program literature refers to resentment as “a grave matter,” and “the number one offender.”

Living in resentment means you are living outside reality. Living in a fictional world between your ears just removes you from humanity, and from the moment. Alone and out of time is no good way for a human being to live.

It all starts with envy. Buffet was right. Go get you some good sins, if you must, at least there’s some pleasure in them. As to envy—as Buffet put it, there’s no upside to it.