Thanks so much for writing this. As a solo-founder I’ve had a very similar experience transitioning from a free web app (GistBox) that I had been working on as a hobby for 5 years to a paid enterprise-grade Electron app: https://www.cacher.io.
While many users using the free app had the same “WHY AM I PAYING FOR THIS WHEN I CAN BUILD IT MYSELF” your users had, there were also a number of folks in companies who felt a sense of relief when I started charging a subscription fee. They knew that this meant I was committed to the project and were more than happy to incentivize its development for years to come.
Best of luck with Sizzy!