Batman is not going to hide from all the lawyers in Stately Wayne Manor.
He'll be a ghost.
Meanwhile, what they think he has in the bank is the tip of the iceberg.
Jeph Loeb wrote a comic where some hood is going apeshit that Batman is burning 10 million in cash to make some point about something... Meanwhile, the Punisher, every drug deal he's ever busted up, he's kept the cash and bought bullets and bazooka's with the proceeds.
(Is it me, or could the IRS spitroast Bruce Wayne?)
Maybe Batman doesn't "keep" all the money, but he would certainly redirect any loose funds out of the world of crime and into nice places, or he'd just bury it for later... Actually if Batman holed up in the Justice League Satellite, 23 thousand miles above sea level, would the rest of the Justice league put up with him proving that he is literally above the law?
Surely space is the equivalent of international water beyond anyone's extradition laws?
Batman doesn't need money to fight crime.
He's a ninja.
He can take down a well armed army with a rolled up piece of newspaper.