This is why I closed my ebay bookstore, bambozzlebooks, (of course keeping the ID functiona)l. It was not scalable. If I wanted to sell more used books, it meant I would have to take more of my time to find used books to sell. I would have to find more books, list more books, and that takes a lot of time. I would have to find more valuable used books to sell.
There is only so much of my time, and there is only so much of yours. Time is limited finite resource. You want your business to be scalable which means you can build a process that can sell ten units of a product or a thousand units of that product. You cannot let yourself be the bottleneck.
The best way to look at this is to build your business from day one planning to sell it from day one.
I read an article by author James Altucher who said the minute he creates a company, he starts to look to sell it. That is smart, because even if you choose not to sell, it is built to exist without you, it becomes a real process, that can build and adapt, and scale.