Let's test that theory

I'd argue it's not comparison at all, but envy. Comparison is a simple act and can be done between two things no one gives a damn about. It's the envy that you generate yourself that ruins joy.
- I'd argue that pedantry on the internet is the REAL thief, here.
  
  Certainly stole my will to live
  
  Pedantry is the main tool in my life-force theft kit
  
  I think this is actually important to point out. Not pedantry at all. You can compare things without becoming envious.
  
  I think we can all agree that pooberbee is the REALLY real thief of joy.
  
  You wanting to have the last word is arrogance and narcissism, should we mention that?
- It is anecdotal, but I used to live in an area where there I was surrounded by people who were richer and more affluent than I was. I didn't envy their stupid luxury SUVs or their unnecessarily huge houses. But it constantly gave me a feeling that I wasn't as well as I could for myself and that I should seek more. Especially when I realized how dumb some of those people who make so much more money than I do are. This ceased the moment I moved to somewhere else where people around me were at my level.
  I think ultimately you want to be at the level that you perceive as "normal". But if you constantly look at people who make more than you, and there always will be, it will be much more difficult to be happy with your situation.
  
  I don't think dealing with the unjust nature of reality is the same as envy. That's ... a whole other situation far more than some tattoos.
- Very zen, and true...
  
  Nothing against this or other stoic ideas, but if you’re the only “enlightened” one while everyone around you is a reptile who is out for themselves, then you just end up a chewed up loser.

Do it with a temporary tattoo and enlist your friend to setup the joke somewhere. Keep your friend and get the goofs

I only know that "compare and despair" variant

Just now realizing the meaning here, before I thought the quote was talking about how people look at an artist's work and immediately compare it to something else.
- ...is that not the meaning ?
  
  it's more saying that comparing yourself or your own accomplishments to those of others will leave you feeling joyless.