I wonder if age and experience might be a component here. A lot of the internet startups quoted as examples of two founders being ideal were founded by really young people. In that context having support might be an absolute necessity. How does that compare with more experienced individuals in their 30's?<p>Having been a solo founder all my life I know just how hard it can be. I would not wish some of the lows I have had to navigate on my worst enemy.<p>If you are unfortunate enough to be in really difficult situations you really need the intestinal fortitude and mental stability to deal with life-changing problems. Few people in their early 20's have had enough life experience to have developed these qualities.<p>The problem with the co-founder model is that when life is peachy everyone is working hard and having a good time. However, when things turn ugly if all founders are not equipped to manage the situation it can easily turn in to a nightmare. Things like not being able to make payroll, facing lawsuits, facing bankruptcy, catastrophic supply chain problems (manufacturing), etc. can easily create a set of conditions that can break apart a partnership that was great during good times.<p>While I will not dispute that having like-minded co-founders can be an advantage, I am of the opinion that --for a certain type of businesses-- I'd rather go solo than run the risk of partnering with someone who might become my worst enemy when things become difficult. The right partner, however, can be an incredible asset, no question about it.<p>I don't think there's an easy universal answer to this question.