My take is somewhat different than posters here. Look at the economics.
Let's say Cam is going to make $250M in earnings. $100M from Football Salary and $150M from endorsements.
By doing what he did, his $150M from endorsements just went down. It's impossible to know, but let's just say by 5%. Or $7.5M.
Now, if I were to tell you that, despite losing the biggest game of your life, you need to go to a press conference and answer a bunch of dumb questions for 15 minutes. Do it with respect and I'll pay you $7.5M. Do it like an A-hole and get $0. What would you do?
That's what Cam needs to be thinking. Play the game, man. Reporters are scum, but that doesn't matter. Treat them with respect and get paid.