"The key word is possible. ...
This balloon will explode, but not without a lot of damage to the pocket books of ignorant investors and stupid banks."
Interesting. Do you know Costco's business intimately? Do you know for a fact that Costco is exceeding the highest possible wage for workers? You have their books? You know all of this?
Or... do you just assume that workers need to be paid the bare minimum? Is it possible that you feel anyone who is not a business owner doesn't deserve a decent wage?
You know what they say about stock investment advice: Use your own best judgement.
Personally, although I will shop at Costco, I would not own stock in Costco. I would own stock in Walmart on the other hand.
Everyone has to make their own investment decisions based on the available information.