It's all about the stadium.
We are going all-in to win now, hopefully a Super Bowl, I assume because PSLs are hugely expensive and Stan the Man wants to sell season tickets. I personally am unlikely to ever see a game in the new stadium, as I am poor and live in IL, but I wouldn't turn up my nose at a Super Bowl or two over the next three years.
But you are right, we are to a certain extent mortgaging our future cap by trading draft picks away to pick up proven players and we will have to pay the piper down the road, perhaps as soon as 3 years.
In the meantime, keep telling yourself that an 11-5 Rams team (could have been 12-4) has in one offseason picked up 4 Pro Bowl level players to add to the team. True SW was high potential, but Cooks is high production and McVay, who knows a thing or two about offense, seems to thing that he is a better fit for the McVay offensive system.
Maybe this gamble will pay off, and maybe it won't, but there are a lot of worse things than having your FO pulling out all the stops to put a SB champion team on the field.