Probably unaware it exists like everyone else. SoundCloud Go has been so poorly marketed.
Up until a few weeks ago, I only ever saw it mentioned on tracks where I could only listen to a sample. On my feed right now, the only link to it is in the overflow menu on the top navigation. Meanwhile, SoundCloud Pro has a big advert which takes up about 1/6th of the page.
Well yeah. There's not even competition there. And shouldn't be really, they are fundamentally different platforms.