I think there is a lot of research to qualify your opinion. A VC backed startup is a very different beast than a bootstrapped startup with a wildly different goal and trajectory. VC-backed startups must focus on market growth in order to make that next round of funding. Bootstrapped startups must focus on product and building strong personal relationships.

Every indication suggests you need a cofounder to achieve success in a VC startup where momentum matters most. In the bootstrapped startup it appears an individual founder is fine so long as the business is built on a valid premise: product excellence and some customer or business partner willing to endure your early failures.