The idea came about when I wanted to post to Instagram, but the API didn't allow it. So I spent about a week trying to automate the process using a phone, with screenshot OCR and a state machine. After a lot of messing around with it, I had a working prototype. Made a website, added a $5/month Stripe plan to see if people were willing to pay for it, sent it to a few friends, posted it on Twitter, and eventually, people signed up and tried it out. It worked, then it didn't work, then I fixed it, then it worked again, this went on and on for a few weeks until it became quite useable.
About two months in, local offices of Toyota and Samsung signed up, and they loved it, money wasn't an issue. That was the moment I realized it may be worth doing it properly.
It grew organically, and I bought lots and lots of Android phones, which are simple workers getting jobs off a queue, and host them in two locations roughly. Phones last for about two years, then I buy new ones (<$100 a phone). Each phone pays for itself in less than a month, server costs are less than $200 a month.
Facebook tried to sue me after I filed for a trademark, we figured it out (I rebranded). Been going steady ever since, but I consider it to be shut down by yet another Instagram move sooner or later. But I said that after 3 weeks of running it, and it's been almost five years I think.
I made it a point to not use any private Instagram APIs, like all my competitors did — instead, I don't emulate the Instagram app, I emulate the person tapping the phone, and use only the official app for it. I think that let me survive this long.