Very loaded question, as the majority of old-world millionaires are pretty much regular people. I'd call this a false choice. (In addition to the obvious answers you will get from this forum, asking you to consider the demographic likely to have stumbled into large BTC holdings -- i.e. engineers, tech-minded folks, cryptonerds and others with strong libertarian tendencies on average.) Again, either the division of the monetary policy in the US pushed you above middle class, or below it. It's the banking cartels and conglomerates, controlled also largely by brainwashed and clueless but regular people who genuinely believe that things are as they are through the magic of capitalism and hard work. Very greedy few at the very top deliberately make the policies that have caused these problems. Everyone else is mostly guilty by not paying enough attention to stop it.

The beauty of a cryptocurrency such as Bitcoin, where the key attributes for this are no/negligible remission and transaction costs and a fixed-supply, is its ability to undermine a huge swath of the traditional tricks in the bankster playbook for siphoning the world's GDP delta. As the world GDP is around 4 or 5% annually, with a fixed currency you could expect holdings (literal holdings) to gain that amount in purchasing power. As it is, our inflation is pegged deliberately at 3%, and may be more since we can't verify this -- and it is more in many countries, and is almost never less (Japan is near the bottem, as they have chosen 1.5% in the recent depressing decision to go inflationary due increasing difficulty competing in trade with countries artificially-boosting their currencies).

Q.E.D., anyone in the US not making an average of at least perhaps 8%, maybe more, on their net worth, is invisibly bleeding money to this deliberate black hole. Ergo, I fully expect BTC to appreciate at a minimum of this amount vs. USD. This assumes the supply-demand ratio remains unchanged (currently demand increases are far outweighing supply increases, which themselves of course are an ever-decreasing function). This also ignores any actual devaluation of USD which may become a factor soon as well.

For these reasons, it is an astronomically poor and uninformed economic decision to not hold BTC as your store of value, and conduct the maximum possible amount of commerce in that currency. I hope we see an explosion of solutions like Coinkite and "reloadable" debit cards (working on the latter myself with the ol' think tank) to permit the ease of users only converting to fiat when necessary and at the last possible minute.