Today, I would personally pick USD as it can be used world wide and for a variety of purposes. However, if BTC were to stop being JUST a speculative asset I would contemplate making the switch. I like being in control of my cash without having to depend on some greedy bank!
Thoughts?
He cannot use bitcoin because he cannot find which store that will accept bitcoin for the payment system.
But soon, after many stores online and offline accepting bitcoin as the new payment system, I guess that he will try to use bitcoin in any transaction, he will reduce his transaction in USD but add more transaction in bitcoin.
When someone can feel comfortable to use something, he will stick with that in a long time.