The comparison
A store at 50% margin needs 2x to break even. At 20% it needs 5x. Same product category, same ads, completely different game.
What that means in practice
The high-margin store can afford to lose auctions, test broadly, and pay more per click. The thin-margin store cannot afford any of it, and every mistake costs proportionally more.
The levers
Raise price, reduce landed cost, or raise AOV. All three are business decisions rather than advertising ones — which is exactly why agencies avoid raising them.