One option would be to add a question to the process for creating an cloud version, where you ask if they've used self hosted and if answered yes ask why they've moved to online.

Speaking from recent personal experience trying to set up our own self-hosted using Docker, which is a modern technology used by a lot of people, the support on the issues page for the official images on git is almost non-existent for Matomo docker, and I'd expect docker to be a common go-to for many businesses and even individual users. There's little documentation on it, issues posted for it can go unanswered for weeks/months. I know I've already encountered something that gives me security concerns (which I made an issue about which was immediately closed without solving the problem) and has effectively halted me from continuing until I learn if anything can be done with it. If others encountered these, and also had a hard time getting answers to fairly important questions, I'd imagine many people would be turned off from self-hosted.