How is this a horror story? Consumer chargebacks/reversals killed your float, and PayPal took action to prevent further losses on their part. They aren't in the business of lending you credit.
Even though this behavior sucks for small merchants, it's not uncommon.
I am one of the customers that got reversed, not the merchant who posted on reddit.
I didn't issue a charge-back and got no option or say on the matter - it was reversed and i got an email from paypal after the fact without any question asked if I'd like to reverse it or not.
It was simply "your transaction has been reversed."
Even though this behavior sucks for small merchants, it's not uncommon.