I am one of those who have already given up on the belief that "high-quality" posts are the way to succeed on this platform

Indeed, when you want to do good on this platform it's all about playing the game right. Putting more time in social interactions along with topics and posts that give gtd upvotes (actifit / steemmonsters / ...). It doesn't take away that steemit is great for people who actually want to have a genuine blog though. Upvote groups are the best way to get some consistent post rewards. I'm not that much a fan of the ones that charge a monthly fee to get a tiny return. Something you did not include in the calculations are the mandatory daily upvotes that have to be given and what about the 10% of the upvotes that go to esteem. Just subtract those and it will likely show that you are supporting them instead of the other way around. This is my main issue with most of these groups.

Good luck building those post earnings, I've been rather passive myself but will start the grind up again myself.