What Do Economics Teachers Do?

Does an economics teacher use what they teach? First this example:

Hi everyone,
I’m just back from Costco where they are selling $100 in Hyatt gift cards
for $79.99. I called the Hyatt — twice, to be sure I got the same info
from 2 different people — and they said the gift cards can be used to pay
hotel charges at the Hyatt Regency in Atlanta for the conference.–Econ Professor Big Name School

Now the puzzler. If you saw an easy means to profit, what would you price these discount cards at? Why didn’t this teacher buy and sell the cards to the list he posted this? Two samples create how much confidence in your decisions?

Now you know why economists can’t get us out of what they taught us into.