The reality is that most software products target companies, not individuals. Individual developers that don’t generate revenue for themselves also won’t be paying for the software they use, and that’s perfectly fine. It really doesn’t cost a company much to keep those developers happy. But developers that are happy with new technology are likely to try and use it at their company. This is the main funnel that JB and many other software companies employ: have a free (or very low-cost) tier that shows individuals how valuable the software is, so that their company can use and pay for the more expensive tiers.
For instance, companies don’t use Flutter because it has a free IDE. They use it because it allows them to cut their mobile development team size in half. Even if it had a paid IDE, it’s almost certainly going to cost the company considerably less than the salary of the developers they no longer need. In Flutter’s case, the “paid tier” isn’t an IDE, it’s Google’s Firebase and other cloud services.
There’s a huge market out there of companies that would rather have a single mobile development team, rather than two. JB wants a piece of that pie, so if they can get more individual developers excited about Compose by making it run on iOS, that will translate to more companies choosing Compose and the paid version of Intellij over Flutter or React Native.