A cursory examination of these companies in their early years highlights the danger of too heavily weighting TAM. In fact, at the time of their Series A rounds, many of the very best venture investments would have had relatively small — or even undefined — TAMs.

The best companies always fundamentally change the markets in which they operate.

Credible adjacencies: In other cases, a startup’s initial product or service is merely an entry wedge into a larger opportunity.

Nascent market potential: Successful startups often ride the wave of a new market that is small today, but will be big in the future, with or without that startup.

if you see an opportunity, don’t let a TAM number stop you from building something great.