It is really hard on maintainers. I think a lot of it is that old adage "It takes 10 positive things to counteract one negative one." And, for some reason, people on the Internet can choose to have any alternate persona they want, and what do they choose? The shittiest person imaginable.
There was a really good Keynote by Brett Cannon last year at PyCon about how hard, emotionally, maintaining OSS is: https://youtu.be/tzFWz5fiVKU?t=3259 -- Unfortunately the official post is buried after 50 minutes of lightning talks. He gets very emotional on stage. I was sitting with him before he gave this talk, it was a very hard talk for him to give, and so very important.
My own story like this: I took over maintenance of a module that had been abandoned, but after the better part of a decade I ran into a time in my life where I have little time for it. It had been languishing, but someone finally offered to help out on the maintenance. Great! I added them to the github project, they started triaging issues, and within a day this guy started spitting vitriol at the new maintainer.
I called this guy out, but he doubled down. I just locked the issue and moved on with my life. But this guy tracked me down and sent me an e-mail to my personal e-mail full of expletives. Followed quickly by an apology:
"I'm sorry, I didn't mean to send that e-mail from my work e-mail address, please don't get me fired."
Literally: No apology for being a jerk, just begging me not to share that exchange with their employer. All of the github comments he had made were removed or severely edited.
And... That person who offered to maintain that module? That was the last time they touched it.