Shows cash generated by each unit/customer to cover fixed costs and growth.
Revenue $100; Variable costs $30 → Contribution margin = (100−30)/100 = 70%.
Treating fixed headcount as variable; excluding third‑party API costs; ignoring payment fees.
Financials slide: show gross vs contribution margin; tie to payback math.
Contribution margin 70% at scale (APIs + payments in COGS).