If Kakfa had come first, no-one would ever pick Postgres. Yes, it offers a lot of fancy functionality. But most of that functionality is overengineered stuff you don't need, and/or causes more problems than it solves (e.g. transactions sound great until you have to deal with the deadlocks and realise they don't actually help you solve any business problems). Meanwhile with no true master-master HA in the base system you have to use a single point of failure server or a flaky (and probably expensive) third-party addon.

Just use Kafka. Even if you don't need speed or scalability, it's reliable, resilient, simple and well-factored, and gives you far fewer opportunities to architect your system wrong and paint yourself into a corner than Postgres does.