I've been objectively successful as a single founder over the past few years, so its definitely possible. I've hired, fired, pivoted, and made more money than I made mistakes but I always felt the lack of a cofounder has been holding me back.

There is only so much emotional weight I can offload onto my amazing wife, and although some of the people I've worked with (contractors, clients) have made amazing contributions - technical, business, ideas, and emotional - at the end of the day I can't shake the fact that I'm alone. I bear all the responsibly for my mistakes and all the rewards of my successes, and even though I've been lucky to have more of the latter the emotional toll of the rollercoaster has been tremendous. When your wife or parent tells you you're doing great or that everything will be OK it helps, but the impact is diminished because of course they are going to support you.

My most successful (although not my most profitable) projects have been collaborations with other talented people both technical and nontechnical, and while the author is certainly correct that a cofounder isn't necessary, I would think long and hard doing anything alone.