Although it is technically a sunk cost, there is a feeling that if you cancel the card, you are just throwing away that $5,000 initiation fee. That doesn't keep me holding on as I have found the card to be valuable for travel... I just hope at some point we get MORE benefits and not less.
Well, by that logic, after two years you've also thrown away another $5k on annual fees and then another $5k every two years hence. Pretty soon, the initiation outlay will have shrunk, as a percentage, in terms of total cost, which is what people should care about rather than obsessing about the initiation fee.
At some point, if the card doesn't meet ones needs, they simply have to get over the initiation fee and move on...
Regards