I think bitcoin is also a good way. Bitcoin is one of the very good choices here as it’s digital currency. You can store your bitcoin even on a piece of paper or use physical wallet. Some rich people who would like to hide some part of their wealth from bank/security accounts. The Swiss bank was a good option to do it but not anymore. The common way is to put cash or valuable goods or commodities but those take-up spaces and you need to find safe space to accumulate them.