Self publishing is awesome because you keep all the money, but it takes years to build an audience.
I can totally relate to that. Some things about self-publishing were much easier than others. Building an audience is hardest so far. Experimented with Google and Facebook ads, stopped because it was too expensive. Email marketing is more powerful in this space than you might believe. Even today.
I stopped that, too, because it did not work too well for me. And also there are quite a few legal implication when you do that in my country (always have been, not necessarily GDPR related).