It'll take me a lot of time to build my own website and content that gives me the same result. So, there's that.
Sorry, not a native speaker.
That being said, I do think a small investment into moving onto your own platform may be worth it, and that might kick in much earlier than you’d think. I use Hugo and a fork of hugo-minimo-theme for my technical and personal writing, and it took maybe three days to set up (granted I have some technical experience). If you paid a contractor to spend a week setting up a statically compiled site with a CMS, you may get competitive SEO without having to worry about content licensing or platform updates. I think statically generated content is generally friendly to search engines. I don’t update my blog infra at all really, and there’s very few steps involved if I needed to relearn how to do it. It is possible to use free open source software and have it get out of your way in terms of making money.
Sorry, but that's just not how it works. The technical part is easy and certainly once piece of the puzzle, but without a certain website age and tons of good backlinks you will never be able to compete with medium.
And your English is plenty easy to understand, no need to apologize about that.
Medium is just easier to spin up than a domain + WordPress. I don't see any other advantages