Building buys an artifact you own. Landing buys a behavior you do not, in a customer you do not control. Those are different purchases with different bills, and the bills moved in opposite directions.
Where the two costs live
Build cost sits inside your org: salaries, compute, tickets, measured in engineer-weeks, front-loaded before launch, highly visible on a board. You see it, plan it, and manage it. Landing cost sits mostly on the customer's side of the glass: their switching effort, plus the sustained GTM attention and change management it takes to move a habit and keep it moved, measured in adoption-months, incurred after launch, and nearly invisible until it fails. Because it is not your headcount, it never lands on a budget line and never gets owned.
The inversion
The full ledger runs twelve lines, but two cells carry the argument: building is collapsing because AI ate a technical problem, and landing is flat because human habit change did not get faster. When building cost three months and landing cost a few weeks, building was rationally the thing you staffed for. Now building is the rounding error and landing is the mountain, but the org chart, the budgets, and the definition of done did not move. That is how twelve builders ship twelve products and land none: twelve times the cheap spend, zero times the expensive one.
The fix is not a tool. Price both columns for your last launch, see that you funded the build and assumed the landing, and move budget plus one named owner to the right column, because that is where the constraint now lives.