I write before work and after work for fun so I figure any income is a bonus. I don't think of it as a "side hustle" that has to earn money, so I don't pressure myself to write every day.
I love reading comments on my stories and knowing someone has read my work and engaged with it. That's more important to me than any money. I see it as "surprise" money and have made a good amount thanks to the Medium bonuses and a few semi-viral pieces.
I just joined in late March, so I definitely didn't start early and don't have a huge following. I also don't self-promote on social media, although I do like to read other Medium stories and occasionally comment (does that count?). I also don't write in productivity, business, or psychology.
So basically, I've just been lucky that I write on topics that caught the attention of some readers. I'm still writing even after the Medium bonuses disappeared because I enjoy writing. But I won't lie--that unexpected money was really nice!