aptitude for exploiting people is not what Y Combinator looks for at all.

What YC looks for, above all, is founders who understand some group of users and can make what they want. This is so important that it's YC's motto: "Make something people want."

If other people both knew about this need and were able to satisfy it, they already would be, and there would be no room for your startup.

the YC partners have to guess both whether you've discovered a real need, and whether you'll be able to satisfy it. That's what they are, at least in this part of their job: professional guessers.

That's what the partners will be trying to figure out: is there a path to a huge market?

This idea is important enough that it's worth coining a phrase for, so let's call one of these small but growable markets a "larval market."

The ideal combination is the group of founders who are "living in the future" in the sense of being at the leading edge of some kind of change, and who are building something they themselves want.

A larval market might also be regional, for example. You build something to serve one location, and then expand to others.

As long as you have some users, there are straightforward ways to get more: build new features they want, seek out more people like them, get them to refer you to their friends, and so on. But these techniques all require some initial seed group of users.

a single question, it would be "How do you know people want this?"

The most convincing answer is "Because we and our friends want it." It's even better when this is followed by the news that you've already built a prototype, and even though it's very crude, your friends are using it, and it's spreading by word of mouth.

In practice, the YC partners will be satisfied if they feel that you have a deep understanding of your users' needs.

one of the best ways to do it is to go talk to your users and find out exactly what they're thinking. Which is what you should be doing anyway.

if the YC partners can convince themselves that the founders both (a) know what they're talking about and (b) aren't lying, they don't need outside domain experts. They can use the founders themselves as domain experts when evaluating their own idea.

This is why YC interviews aren't pitches.

if you don't know the answer to a question, don't try to bullshit your way out of it. The partners, like most experienced investors, are professional bullshit detectors, and you are (hopefully) an amateur bullshitter.

you should know who your competitors are, and tell the YC partners candidly what your relative strengths and weaknesses are.

This is seed investing. At this stage, all they can expect are promising hypotheses. But they do expect you to be thoughtful and honest.

If the partners are sufficiently convinced that there's a path to a big market, the next question is whether you'll be able to find it. That in turn depends on three things: the general qualities of the founders, their specific expertise in this domain, and the relationship between them.

what seemed to them an irrelevant story was in fact fabulously good evidence of their qualities as founders. It showed they were resourceful and determined, and could work together.

Mundane as it sounds, that's the most powerful motivator of all, not just in startups, but in most ambitious undertakings: to be genuinely interested in what you're building.

The ones who become really rich are the ones who keep working. And what makes them keep working is not just money. What keeps them working is the same thing that keeps anyone else working when they could stop if they wanted to: that there's nothing else they'd rather do.

The founders who are doing it for the money will take the first sufficiently large acquisition offer, and the ones who are doing it to seem cool will rapidly discover that there are much less painful ways of seeming cool.

This exploitative type of founder is not going to succeed on a large scale, and in fact probably won't even succeed on a small one, because they're always going to be taking shortcuts. They see YC itself as a shortcut.

What do users want? What new things could you build for them? Founders who've become billionaires are always eager to talk about that topic. That's how they became billionaires.