People are reacting because they are left feeling ripped off and looking like idiots. Even if it only for a measly 10$; most people hate those feelings. It is made even worse when the person who you feel took advantage of you is gloating and ridiculing the whole situation in public.
The feeling of being ripped off is even worse when you believe (however erroneously) that you have some sort of friends-type relationship with that person.
Following a YouTuber, and even getting acknowledged in their comments, isn't really a relationship. It's para-social, because they're only interacting online, for a limited time, with what the YouTuber has chosen to show of themselves. For lonely people who don't have a lot of friends, being greeted in chat when they log in can help them feel like there's a genuine relationship there, but it's not.
And people constantly project their own desires onto others they don't even know--celebrities and their stans are a thing. Well, Chantal, sad as it sounds, actually has stans, who identify with what they believe to be her struggles, and when she started her OF they wanted to be supportive.
So it's not so much about the money as a massive betrayal of trust. They helped her in good faith, and she's taking their money, bailing on them--and lumping them in with the haydurs, to boot.
These are people who have probably thrown a lot of superchat money at her on her livestreams, and now they're not going to do that any more.
One of the hardest things about having an online audience you interact with is managing those kinds of parasocial relationships. Followers will come up with their own ideas of who you are and what you're really like, and how much of a bond there is between you, because they don't really know you, and their minds fill in blank spots by projecting their own desires onto you.
It's very weird, can be unsettling, and you have to keep making a lot of careful, private decisions about how to gently discourage it, or at least not feed it. And when you're someone like Chantal or Jude Valentin, whose content and persona appeals to some seriously broken people who project like mad, they're going to fuck it up because they're broken themselves. As we have just seen.
People on here are right when they say scamming people out of money is one of the few things that probably won’t be forgiven by Chantals supporters - Amber had the whole gofundme cancer scam thing for her girlfriends mum that people STILL get mad at her for. This won’t go away anytime soon.
And don't forget Tess Holliday's t-shirt scandal, in which the proceeds were supposed to go to a domestic violence charity. Tess claims she hired a company to handle fulfillment after she got so swamped with orders she couldn't handle them all, and lot of people still never got their t-shirts. And if anything did go to charity, it was a token amount.