here's my take - the hardest part isn't doing more computer programming, it is context switching between technical and sales. It has been done, so it is possible, but it is very difficult as people said.

very few computer programmers have good business insight. we know how to build cool stuff, but most of the cool stuff are either - unable to directly bring values to people or cool but no one cares. that's why we need a cofounder, ideally, a person closer to product/sales, who can help you to make connection, understand what people want, shapes product... all the non computer programming stuff.

also - we tend to work in isolation when being the only founder. at least for myself, i sometimes live in my own head, which can be very far from reality...

despite that - i share the same sentiment with you and will not give up trying to found a business :)

Yes, switching between development and sales/marketing is probably the hardest aspect for me.

Most years I have a booth at an industry trade show. For a couple of weeks preparing for it, the week during the show, and a couple of weeks after that, following up with potential customers I met at there, I find it virtually impossible to get an development done.

Also, onboarding new customers with my software is usually labor-intensive. So that also takes time from development.