That $1818 bought miles, transport, and status. One has to allocate here.

When miles were more plentiful, I'd buy my ticket for summer family travel, but get the family tickets on miles. This allowed paying once not thrice for the ideal schedule, no matter what the (elevated) fare. Nevertheless, a mile rarely replaced more that 1.5 cents cash, used this way. 20,000 miles * 1.5 cents + $550 copay = $850. But, as others note, would I actually pay this?

I did just use 80,000 miles to secure my wife Global First FRA-SFO for her November return from Florence. $10,298 to buy with cash, or 12.9 cents/mile in "boasting rights" USD, not a real currency. That's a $4,378 bump from Business and the upgrade is available. I'm actually spending what I value as $1200 in miles, rather than spending $728 each way coach, a $472 difference. That's actual money I could put in my pocket and spend a different way.

So $500 for a GPU? In bringing my 1k PQDs up to $10,000 this year, that's not far off. It may not be a rational choice, but it's a choice many of us are making. (Istanbul was great, and so were the beds both ways.)