it's a waste of mental energy to drag yourself down based on events that happened in the past

I completely agree.

But I'm trying to make the distinction between "don't obtain debt" and "don't pay debt".

if something was a mistake in hindsight, you can avoid those mistakes in the future

There's a word for the process of concluding that something was a mistake: regret.

I think the difference in understanding comes from what we put into the word.

Regret is a word loaded with emotion.

If the purpose is to say "don't beat yourself up endlessly", I 100% agree.

But beat yourself up a little and let go. :-)

Preventing mistakes requires regretting them.