In terms of sustainably feeding ~8 billion people in a finite world - "spending" 2 pounds of seafood (bait), plus all the overhead of fishermen / boats / fuel / etc., to get 1 pound of seafood (lobster) - that is far, far beyond mere batsh*t crazy.
Turning less tasty food into tastier food at a 2:1 ratio honestly does not seem all that terrible in the big picture.
They’re expensive largely because of the infrastructure required to keep them from going bad.
That bait (herring) is food to a whole lot of people. It has been overfished to support lobster farming, it was taken at cost from the commons to develop a food that few can consume.