When thinking about Devers or any other star player, there is always a point where trading that player for prospects is better than paying that star. Just look at the Rays. That is how they built their team, develop stars, trade them for more prospects, let some of the prospects become stars, trade the stars for more prospects, rinse, repeat.
The trick of course is knowing when you are paying too much and being able to pick the right prospects. In general though, paying the mega contracts tends not to work out (Bryce Harper, Albert Pujols come to mind). Mookie Betts started out seeming like a really bad deal for the Sox but already is looking better. I hope we do sign Devers but there is a point where it is better to trade him.