Unfortunately, it's a part of our sport. And maybe you'll never see DNF behind your name, but many of us do. And what's important, understanding what that DNF means...
There are far greater details behind a DNF than just Did Not Finish. It means you did not finish the race you started (not to be confused with DNS which is Did Not Start). It can also mean, my tire blew up beyond repair or another bicycle malfunction, I got in a wreck, or I got sick or had another medical condition. There are a multitude of factors to accept when starting triathlon and a whole bunch more when you're trying to finish a triathlon.
The gravest of them all, it can also mean, "I quit".
We preach, don't quit. Quitting is giving up. It's surrendering to failure. It's defeat.
For me, quitting is not an option. I've had many conversations with myself in the midst of a race. I have felt mentally (and just at Ironman Barcelona a few weeks ago) physically ready to withdraw. I realize the temporary ease of being done. But I also consider the permanent virulence I would hold against myself.
Thus, quitting is a very personal choice.
We can never be in your head to discern why quitting became an option or why it's okay with you. And guess what, we will judge you based on our own notions no matter what. Yes, you will be judged. You can imagine my face, eyes wide, mouth open and a look of confused, "I'm sorry, you what?" ~unable to understand that word... quit.
While DNF can mean "I quit",
"I quit" can mean, "I'm not ready".
My point, and a lesson learned in a moment of understanding, compassion, and excitement...
quitting isn't all-or-nothing. It doesn't have to be giving up or permanent defeat.
I'm not saying it's okay in my mind or even acceptable...
But her/his decision to quit was justified in his/her mind. It was acceptable and necessary to him/her in that moment. And now there's a new choice. Give up or try again. Quitting doesn't have to be forever.
Caught a DNF? Feel it. Accept it. And challenge yourself to defeat it. Try harder. Train stronger. Be more confident. Iron out your "quit". And do it again.