One joke extension, 12K users, $400/mo — and why 10% conversion still lost the game

Six hours, zero servers, $400 a month that costs nothing to collect. The operator built a Chrome extension that swaps words on every webpage—"AI" becomes "magic," "crypto" becomes "monopoly money"—and 12,000 people installed it. 10% upgraded to the $3/mo pro tier for regex and per-site rules. The comments called bullshit on the math (1,200 × $3 = $3,600, not $400), but the shape of the case is real: a weekend joke that monetized, then stopped.