I hold 1,200 Bitcoin in over 200 wallets, the fruits of getting into the currency early on, and earning Bitcoin through mining. I am not particularly interested in money and rather prefer to be called a "Bitcoin Whale" than a "millionaire".
At today's exchange rate, my 1,200 Bitcoin has a a fiat value of 15,583,560 US Dollar; my bank balance with Barclays Bank is just over $10,000; this means that my "wealth" is made up to the tune of 99.94% in Bitcoin, and 0.06% in fiat currency.
I am going to keep it that way. If I feel the need to buy a $100,000 car, exchanging that amount of money into fiat currency and sending it to my bank will only lead to a flurry of calls from them asking me to "prove" the source of my funds - whilst they freeze my account and earn interest on it. If the seller of the car doesn't accept Bitcoin, I don't buy it; it is as simple as that. The same goes for a house or any other capital purchase.