Myth: a winning native campaign scales linearly — just raise the budget.

Myth: a winning native campaign scales linearly — just raise the budget.
No. A buyer had a native campaign at $500/day, cost-per-sale $22, rock solid for a month. He took it to $5,000/day in a week. Cost-per-sale: $58.

Why? At $500 the algorithm cherry-picked his best 8% of inventory. At $5k it had to fill — opening the bottom 60% of placements, low-intent slideshow tails, and incrementally worse audiences. The marginal click cost far more than the average.

When he capped per-publisher spend and scaled by adding new sources instead of inflating one, cost-per-sale held at $26 to $4k/day.

"It scales" almost always means "it scaled until the good inventory ran out." The average hides the brutal marginal.