I don't think the collapse of the scheme had to do with not being able to get more cases. I think it all turned on his ability to keep juggling things.
In Madoff's case, the 2008 financial crisis couldn't be controlled. In Tom's case, he couldn't foresee the pandemic -- it closed the courts and halted day to day business that he had been able to capitalize on in the past. I'm thinking it caused an unavoidable lag time that his juggling ability wasn't able to cover or bridge quickly enough to keep his head above water. My half-baked theory, anyway.