Kupp is worth a 1st round pick.
Donald is worth more than any 1st round pick. He's worth at least three 1st round picks. Greatest D tackle of all time shouldn't sell for chump change.

Plus, as a fan, there is a good feeling of satisfaction or joy in seeing the great players of our team remain until they retire. I'd be open to trading them but it would have to be for a good chunk more than what you featured.