I am fascinated by the work of Paul Graham. He changed the way we build startups, but that does not mean I agree with everything he writes. His opinion of solo founders is one of them.
PG argues that:
1) A founder starting a company alone is a founder who couldn't get his own friends on-board, thus proving a lack of leadership ("vote of no confidence")
2) "Starting a startup is too hard for one person [...] you need colleagues to brainstorm with, to talk you out of stupid decisions, and to cheer you up when things go wrong"
3) "The low points in a startup are so low that few could bear them alone. When you have multiple founders, [...] Each thinks "I can't let my friends down." This is one of the most powerful forces in human nature, and it's missing when there's just one founder"
Graham was so intransigent on the idea that you need a co-founder, he forced Drew Houston (Dropbox's founder) into finding one in two weeks to get into Y Combinator. It went well in the end, good for him. What about the countless startups that shut down because of a co-founder breakup?
My first startup failed after one year. It was time to scale but our visions were different. A great co-founder relationship is about 3 things: friendship, alignment, and dedication.
It's pretty famous that co-founding a startup is like getting married.
Friendship: If your significant other is not your greatest friend, it won't end well.
Alignment: If one wants kids, but not the other, it won't end well.
Dedication: If you are less committed than your spouse in the relationship, the breakup is imminent.
It is objectively hard to find a great partner in life. Finding a partner for the sake of it is the surest path to self-destruction.
Not everyone has friends who have the exact same interests. Hell, that would be boring. Friends don't necessarily have the right skill set or are too afraid to leave their situation. And who can blame them? You have to be a little mad to build a company. You can just work in an office without having to worry about tomorrow. The American mindset ignores the cultural specificities of the rest of the world. Not everyone is comfortable with risk or change, and that's okay.
Building a startup is like traveling: it is better to go at it alone, then find like-minded people on your way.
You can be alone, but you don't have to be lonely.
Stay close to your users, stay close to your friends and family.
Join communities. In the olden days, master artisans, who represented a big part of the business owners, had no co-founders. Instead, they could rely on a guild. Surround yourself with makers, doers, and enthusiasts.
It is easy to give into fear when you feel lonely. Only cowards settle down for the first familiar face that offers them some sort of immediate attention. Work on yourself and others will eventually be attracted to what you want to offer.
If not, your idea sucked in the first place. Don't give up. Move on.