They are absolutely worth it if they are good. A guy like Dak (unless proven wrong) I'd rather let walk and start over again. A guy like Tom Brady, Rodgers, Wilson, Mahomes, Stafford, Rivers, Luck, Big Ben, Brees and Ryan all deserve any amount of money they can get. A guy like Dak I would never give a large chunk of salary cap space to. I would rather roll with a cheap rookie than Dak at a large long term contract. Dak is not going to win a super bowl. If he ever wins a super bowl it's going to be a Trent Dilfer type of win. Never in a million years did Trent Dilfer ever deserve to be paid a huge chunk of Salary Cap space.
I fully understand what you're saying. QBs get paid whatever chunk of salary cap space. Salary Cap goes up every year so that means QBs contracts will also go up. It's simple. It's not hard to understand.
At this point Dak has not proven to be worth taking up such a large chunk of salary cap space. I hope he goes out this year and proves he is worth a huge chunk of salary cap space.