I was among the naysayers. I first met Drew at pg's house just before Dropbox did YC. I listened as he explained Dropbox, and I immediately thought of a dozen reasons why it would be very difficult and probably fail (I'd recently worked on something very similar for a month or so just to figure out whether it was a direction I wanted to go with my own company, so had some familiarity with the scale of the problem...I…
However, Drew took me out to lunch about 10 months later. They'd just signed their Series A with Sequoia (although it wasn't public knowledge), and were looking to hire their first couple employees. Aston had just been hired the day before as employee #1; Drew was wondering if they could interest me in being employee #2.
At the time, I had my own startup that I was trying to get off the ground with a friend from college. I could tell Drew was wicked smart, and he was way more prepared and ready to bring a product to market than we were. But my immediate response was "I can't leave my cofounder, and I want to see where my startup ends up going." He was very understanding, and said "Yeah, if I were in your position - when I was in your position [DropBox is Drew's second company] - I wouldn't give it up either." I couldn't help thinking, as I walked away, that maybe I'd just passed up the best opportunity I'd get in my life. They filled their positions with a couple MIT grads later that day.
A couple years later, after I'd moved out to the Bay Area and was working for Google, I saw Aston at Maker Faire, and mentioned that maybe I'd made a mistake in passing on DropBox. He said, "Naw, you made the decision that was right for you." And in hindsight, I think that's correct. I had 3 dreams coming out of college: one was founding a startup, another was inventing a programming language, and a third was learning how Google Search works. This way, I got to try my hand at all 3 of them. And I'm not sure DropBox would've succeeded the way they have if they'd hired me: they got some kickass early programmers instead, and I had some growing up to do before I was really ready to start something big.