Madoff confessed to his sons and said he was imminently going to surrender to authorities, his sons called the FBI, the FBI interviewed him at home (no arrest, no warrant, no indictment), and he confessed to the scheme being a large scale fraud to the FBI.
And Madoff was physically within US jurisdiction.
And Madoff had much clearer records and much less complicated an organization that the FTX network of companies, which seems to have been highly optimized to conceal specific evidence of fraud and theft by, between, and by insiders against the companies in the network.