I don't think she was expecting to get rich quick from only fans. I do think she needs the money, and she saw it as an easy solution. I also think she gets off on it a little, because it satisfies the histrionic part of her personality disorder cluster, which manifests itself in gross sexual display and acting out.
Regarding those money issues, I do think she is living beyond her means (if you can call it living). Her years old-claim that she spent $1000 a month on takeout, which shocked everyone, always struck me as a gross underestimate; I think $1500 is more like it. I also suspect that this has gone up in her immobile "covid" era, when she plops down $70 for lunch, and then another $70 for dinner. She is probably well over $2000 a month (which is only $66 a day and only $52 a day in US money) by now. The rent is $1500 on top, which is a $3500 nut to pay even without fixing the car. This does not include the daily boxes arriving from Amazon, which conservatively must add up to another $1000 if she's spending a hundred bucks on just candy. So make that $4500 outflow. Peetz probably kicks in his half of the rent, but she's still stuck with the rest. She would need to break $4000 a month on YouTube to just tread water, month in and month out. I don't think she can do it, and I think her credit is on its way to maxing again.
So: Only Fans provides a solution. I don't think she expected to get rich from it fast, and I think even she was a little surprised to get the $1000 windfall, which had her jazzed enough to boast about it excitedly. She is accustomed to failure when she starts such things anyway, and she had no reason to expect differently (this is a flaw in my theory-- she always expects a different outcome when doing essentially the same thing) I don't think she would quit because she is disappointed in the money. On the contrary, I think she would really like to hold on to that money; if she is quitting, it is for other reasons.
Why she quit if she has in fact has quit (remember that she hasn't said that she has quit yet) is unknowable for now. I guess we have to wait and see how she spins it. I don't think her "critical issue" is another health crisis; she wouldn't frame it that way. The speculations I have seen, ranging from being creeped out by requests, disgust at herself, ire at having her content stolen and income stream disrupted, anger at her fans for being against her, fears of embarrassing stuff circulating on the net...they all seem plausible, but none seem likely in and of itself to be a "critical issue".
It is entirely possible that her critical issue is something entirely stupid and illogical; that's just the way she rolls.
But I gotta hand it to her; her cliffhangers are usually pretty good.