The criminal complaint claims he made 600K in commissions. That doesn't mean he still has all that money, though I'd be pretty amazed if he didn't have a lot of it. He didn't exactly seem to be blowing enormous amounts of money if descriptions of his living arrangements are accurate (i.e. renting a share of an apartment for $1K/month).
They won't drop charges, but when it comes to sentencing, they're a lot more likely to throw the book at you if they know you're hiding a huge amount of money for when you get out. He would be well advised to consult real legal counsel (other than a public defender) as to how to construct a binding deal on anything reducing sentences/getting charges thrown out in return before he says a word. It would certainly be idiotic to turn over the keys in return for nothing.