Satispay
Satispay has unusual unit economics for a payment system. The choice not to charge private users — the foundation of consumer adoption — meant that every private-to-private transaction generated zero revenue. Revenue came only from commercial transactions (fixed commission of €0.20 + 0.5% to merchants).
This created a unit economics challenge the team knew from the start: the model required building critical mass of private users first (costly, no revenue) before merchants had an incentive to join (which generated revenue). It was a double marketplace with one free side.
Merchant unit economics were positive from the start: a lower commission than Visa/Mastercard, with zero POS hardware cost for merchants using QR codes. But acquiring merchants without users was impossible, and acquiring users without merchants was much harder.
Satispay solved this sequentially: first built the user base through peer-to-peer word of mouth (near-zero CAC), then used that base to convince merchants with data ("your customers have been asking for us"). Each acquired merchant increased value for users, who acquired more users, who acquired more merchants.
The flywheel took years to spin fast enough to generate profit. But once it started, it was nearly unassailable.
Two-sided models with one free side require explicitly planning the break-even point and having a funding plan that covers the gap. Patience is not free — it has a capital cost.