They've already proven their business model, have tons of customers, are making a profit, and have a plan for scaling their business. This is the perfect time t

They've already proven their business model, have tons of customers, are making a profit, and have a plan for scaling their business. This is the perfect time to take investment - regardless of whether they were bootstrapped to this point. I don't think anything in the so-called "lean startup" philosophy runs counter to the idea of taking Series A financing when appropriate. Hell, even 37Signals took money from Jeff Bezos...