Jeff Clavier angel investor, Founder and Managing Partner, SoftTech VC
“I look at the three typical factors [when investing]: the team, the product, and the market.”
Here are his market considerations.
“Is it feasible in, say, three, five, or seven years to build a company that’s going to go to $50 million or $100 million in revenue and not be the only player in the market? If you own 50% of the market and you’re a $100 million company, then that’s interesting.
So, I figure out the market opportunity, is it big enough?
 [Clavier’s ultimate question]: how can you build a team that really has a scalable product into an interesting market? 
Do I see this company being able to produce revenues of $500 million using the sort of trajectory of customer acquisition, traction, monetization, retention and so forth, based on what they do?  If the answer is yes, and they are not the only player in the market  you see at least a $1 billion or $2 billion market.” Jeff Clavier, Seed Capital From Angel Investors: Jeff Clavier, Founder And Managing Partner, SoftTech VC; July-Aug. 2010; http://www.sramanamitra.com/2010/07/28/seed-capital-from-angel-investors-jeff-clavier-founder-and-managing-partner-softtech-vc-part-1/