It's not necessarily incompatible: authors can make money in ways that don't depend on enforcing IP or even the number of books sold. For example, Patreon, Kickstarter, government subsidies, payment for number of books written, grants, etc.

However, all those other ways are more difficult to set up, and can be risky for the funders, so IP enforcement is the least-worst solution.

Commissions, grants, advertisements, sponsorships, donations, teaching... There's already an enormous ecosystem of artists and authors who work outside of the copyright realm (blog writers, substackers, social media artists, youtube creators, soundcloud rappers) and who make money enough to pursue their passion and whose business model would be totally unchanged if copyright were abolished entirely tomorrow. When their work is downloaded or shared or copied or linked or edited or remixed they appreciate it and see it as a multiplication of their artistic impact.

I dunno, the same way they did for decades with public libraries?