Mortgaging the future? Depends on your perspective.
One, you get an immediate top-3 player at his position where there’s very little elite talent. You also have that talent until 2027 without an extension.
The other, you’re giving up essentially 10 years of prospective play from 2 different positions. A chance to recoup future picks with trades or a chance to have better commodities to trade up for someone you believe to be elite at 5 of those 10 years at a team friendly cost controlled basis.
Your last point is the most important. If this team feels Garrett, or any player fetching that price, can move the needle then they do it.