Hindsight is 20/20 but since Fields was available at 10 does it make overpaying Dak look worse? They could have given Dak the franchise tag and maybe trade him after drafting Fields.
Realitically, since Chicago was willing to give up future 1st's to go up & give away the store to move up for Fields, if we let Dak walk... then Chicago just moves up a little higher and steals him out from under us anyway. So we walk away from the draft with a hole at QB but Surtain or someone falls to us... so we're slightly less terrible on defense (still bad at safety and on the d-line and at linebacker, but with a nice new cornerback to help polish the furniture on our sinking ship of a defense) but we're not able to function on offense because of the the hole at QB.
Or, worse, we beat the Bears' trade offer, so we're giving up a future 1st and probably tossing in Gallup since he's one of the only trade chips we have that anybody would want. In which case, our defense is staying terrible and our offense is still getting worse (because rookie QB's are basically never as good as Dak so they're all a downgrade even if they aren't an awful bust). It'll be 2023 before Fields gets to QB a team with another 1st round rookie on it to help the cause, and it'll be 2023 before the defense gets a 1st round resource to help it. Fields will already be set up to be just another Romo or Dak as the next guy to accomplish nothing here because the team couldn't be bothered to field a serious NFL defense.
And while I'm no huge fan of spending premium resources on 4-3 linebackers, one of the nice upsides of picking Parsons is that it softens the ground for convincing Jerry we can move on from Jaylon's albatross contract soon and for avoiding screwing ourselves by committing to a similar albatross contract with LVE. If we let Dak walk, the way the dominos fall, I think it's pretty likely we come away locked into Jaylon and LVE remaining the future at LB. Which is a losing path.
Oh, or maybe Jerry panics after Chicago steals Fields out from under us and so he picks Mac Jones at 10. Which: yikes.