When the iPad was released in April of 2010, I was a second-year Maths student in Australia. I received the iPad on the first day it was released, and I was immediately impressed by the possibilities of a large touchscreen.
Programming has been my hobby since I was ten, but being able to "touch" the app was an amazing new experience. The first app I wrote for the iPad was called "Cheatsheet Viewer" for viewing cheatsheets related to programming such as Git commands. It was sold about a hundred times on the first day, but the sales quickly wound-down to about ten copies a day, so I was back to focusing on my studies.
Most Maths students prefer handwriting because it is easier than typing out equations. I would re-write a lot to make cleaner derivations; sometimes I even tore out some pages and threw them away. There were often pages of loose papers lying around my desk, torn off from my notebooks with derivations I wasn't happy about. By the end of the semester, the notebooks were already too messy and they were all gone when the new semester started.
The iPad seemed like a very good solution to the problem except it didn't have a good stylus, but being able to never lose the notes again and being able to correct mistakes easily were good enough for me. So when the new semester began in June, I was searching for a good app for taking handwritten notes on iPad. There were already a few popular apps at the time but none of them fit my needs perfectly. So in November, the quest of creating the perfect handwriting app began...
I spent the entire semester break working full time on the app, and then used all my remaining elective course quotas to pick courses that I already knew for the last semester, like two introductory courses on programming. I skipped most lectures and only attended the exams. It was a hack to spend more time on GoodNotes. I had the worst grades in the last semester because I didn't spend enough time on the assignments and exams, but was compensated by the successful launch.
I had a secret wish to not having to find work after university because I was an introvert and didn't have the education credentials to become a professional programmer. Picking the science degree was a way to explore new things but it also gave me anxiety when I was closer to graduation. GoodNotes was my last hope. It took all my remaining energy to make the final bet. Very luckily it was featured by the Japanese App Store soon after launch and word-of-mouth has been driving the downloads since then.
In the first few years, I had been the single person doing all development, customer support, and (little) marketing. It gave me a lot of freedom to travel and to work any time I liked. On the other hand, there was so much that I needed to do like bug fixes or helping users because there was no one else, and there is a bigger vision gradually emerged that I cannot do it myself. As you may guess, since 2016, the GoodNotes team is slowly assembled together to achieve the bigger vision.