This assumes time is an infinite and valueless resource.

Unfortunately for most people, time is a finite and precious resource that is already wasted far too much.

I agree, but if some idiot tell you mean things, you will hear it anyway, and it might ruin your day, even if you know those are best ignored. My solution is the best for my own mental health: i acknowledge the criticism, i use bit of a socratic method if they are available (not as a rhetorical tool, but to achieve understanding for myself), and then i ignore them.