Well, the article was published in Nov 2017 and it neglects to mention at what price he went in at. If he didn't sell in December, I hope he was able to stomach the swing from then until now. But at least he is in profit currently.
And he's basically invested in bitcoin and doesn't transact with it much.
"...But you can hardly pay for anything with cryptocurrency. And products such as special debit cards that could change that are still in their infancy. What do you guys do when you want to go to the bakery in the morning?
We pay with cash. Until now we've been paying for most things in Euros. We rented a garage, where we keep things that we own. Every day we try to sell something from there, sometimes for Euros, sometimes for Bitcoins..."
So no, he is not 100% bitcoin. He still needs fiat.