Claim
The default mistake in marketplaces is to balance both sides simultaneously before anyone has product-market fit on either. Pick the hardest side (90% of the time, supply) and nail liquidity there first. Use crutches like Craigslist to hack the other side temporarily. Marketplace dynamics — pricing, take rate, network effects — only matter once liquidity exists.
Mechanism
A marketplace with no liquidity is two empty rooms. Both rooms can't be lit at once because each side waits for the other. Picking one side and hacking the other gets one room lit; once it's lit, the second side fills naturally because it has somewhere to go. Trying to grow both sides equally produces undersupply on both, no transactions, and an early death. The early-stage operator's job is fill rate, not theory.
Conditions
Holds when:
- The product has a clear sided structure (drivers/riders, plumbers/customers).
- Crutches exist for the easy side (Craigslist, classified ads, manual recruiting).
Fails when:
- Both sides are genuinely peer-to-peer with no asymmetry. Some marketplaces don't fit this rule.
- The crutch attracts the wrong kind of demand — supply gets demoralized by a flood of unintentful demand.
Evidence
"Pre-PMF, stop theorizing marketplace ratios. Pick the hardest side (90% of the time supply), nail PMF there first. Use crutches like Craigslist to hack the other side temporarily. Fill rate (intentful demand converting to transaction) is the output metric."
Lyft built driver supply to reach 1% of US workers. Pre-launch in each city, the team focused on supply density first; demand crutches kept the other side warm.
— Benjamin Lauzier on Lenny's Podcast, 2026-04-28
Signals
- Fill rate (intentful demand converting to transaction) climbs week-over-week.
- Proxy metrics for liquidity (ETA, available providers, response time) hit thresholds where conversion saturates.
- The team can articulate "we're in the supply-build phase" or "we're in the dynamics phase" explicitly.
Counter-evidence
Some operators argue both sides need investment from day one because supply quality determines demand retention. Lauzier's view holds for marketplaces where supply is the genuine bottleneck; in inverted cases (demand-constrained categories like rare collectibles), nail demand first. The principle is "pick the hardest side"; the application varies by category.
Cross-references
- Use peer mentorship instead of HR overhead to scale supply quality — the supply-side scaling pattern that supports liquidity work