People tend to underestimate how much things can change, and this causes them to undervalue ideas that aren't viable now but could be in the future. - Paul Graham

College students mostly think what their teachers tell them to.

Use difficulty as a guide not just in selecting the overall aim of your company, but also at decision points along the way. At Via web one of our rules of thumb was run upstairs. Suppose you are a little, nimble guy being chased by a big, fat, bully. You open a door and find yourself in a staircase. Do you go up or down? I say up. The bully can probably run downstairs as fast as you can. Going upstairs his bulk will be more of a disadvantage. Running upstairs is hard for you but even harder for him. What this meant in practice was that we deliberately sought hard problems. If there were two features we could add to our software, both equally valuable in proportion to their difficulty, we’d always take the harder one. Not just because it was more valuable, but because it was harder. We delighted in forcing bigger, slower competitors to follow us over difficult ground. Like guerillas, startups prefer the difficult terrain of the mountains, where the troops of the central government can’t follow. I can remember times when we were just exhausted after wrestling all day with some horrible technical problem. And I’d be delighted, because something that was hard for us would be impossible for our competitors.

The more you realize that most judgements are greatly influenced by random, extraneous factors—that most people judging you are more like a fickle novel buyer than a wise and perceptive magistrate—the more you realize you can do things to influence the outcome.