it's VERY risky carrying large sums of cash!. if Police stop you for any reason, and they ask to search your car, and you say yes, and they find the cash, they take it, and it's up to you to sue to get it back!. it could take YEARS, or you may never get it back!. meanwhile, they use your money to fund their department!.. one example here, but there are MANY others!.
Police abused civil forfeiture laws for so long that the Supreme Court stepped in. But one ruling won'''t end it. btw, if you say no to a search, they will send for a drug sniffing dog, if you don't know you don't have to wait for that according to the Supreme Court, and when the dog gets there, they can claim the dog smelled drugs, or just make the dog alert on command, and then they have probable cause to search your vehicle and seize your cash!..