> So, the real question is if you can build a prototype, gain traction and make revenue, why is it still frown upon that you are a solo founder. I believe the

> So, the real question is if you can build a prototype, gain traction and make revenue, why is it still frown upon that you are a solo founder. I believe the reason is because the odds of you taking this product and turning it into a company are less in your favor than if you had others to consult in your business practices. It's less about "startup cost" and more about having two or more heads in the problem space. There's a reason that critical applications often have multiple people running the show -- it's too easy to make a mistake and it usually requires more than one head to get right. It's not impossible, just hard. So from an investor's perspective, think of it this way: You're approached by 10 companies. (Or in YC's case, hundreds.) Many of them have a "prototype, traction, and revenue". They all look reasonably appealing. So which do you choose? The ones with multiple very smart founders? Or the ones with a single smart founder? Which of those will be more successful? Which will be able to more effectively hunker down around the whiteboard and come up with some new brilliant ideas when the times get tough? OK, how about a harder one: You have one company with a bunch of smart founders but only a concept, and you have another company with one founder but a "prototype, traction, and revenue". Now which do you choose? This gets more difficult, but I'd argue the former choice will have a better chance at success, given equal capability of the founders. The former has validation in the form of N people believing in their company, and the latter has real customer validation. But the former has better /potential/ in terms of coming up with something valuable, whereas the latter has more potential to fail at scaling their business. This of course depends on a lot of factors though, and maybe the latter's prowess in building a prototype, gaining traction, and making revenue is convincing enough that they can make it through the long haul. Case in point though is that for a VC, it's a numbers game. And with all else being equal, if you can invest in 4 smart people instead of 1, your odds of return are higher. Also, to your first point, after you're making real revenue and/or have funding, nobody cares about how many "co-founders" you have. This is true. They care instead about how many people are on your team. Ends up really just being a semantic distinction based on your company stage :P.