I think that his point was that he's not selling at under 50k/BTC, so it's about the price, not the amount he's selling.
Yes, I understood that.
Even more, leaving with 50k EUR may not be great (we're not in the Shengen yet, remember?) and also depositing such amount to a bank (even more, one that's foreign for him) may rise questions.
Well, in the theoretic case when OP has BTC worth of 50.000 euros, he could also make multiple visits to Bucharest and sell for values of 9999 euros, thus he would not be coerced to declare the money. Even in this situation (let's suppose he makes 5 visits for five
I will add that (I remember your story on Greek airports!) if he returns too quick from Bucharest may also rise some eyebrows 
All in all, the suggestions are not bad, but I'd do that only together with an actual vacation or at least city break. This way the price of the plane will actually worth it even for much lower amount of bitcoins sold.
All in all, the suggestions are not bad, but I'd do that only together with an actual vacation or at least city break. This way the price of the plane will actually worth it even for much lower amount of bitcoins sold.
I added here a hyperlink of the story you mentioned, for everybody to understand. Excepting that, the idea of a vacation is not bad
OP would certainly have many places to visit here, including Dracula's castle I realized something else: why would anyone buy 50k in Bitcoin with cash? Exchanges are less risky, and leave a paper trail to explain your spending to taxes. Unless said person doesn't want a paper trail, for instance because it's criminal money. By that logic, it's more likely you'll be dealing with criminals than with honest people, which significantly increases the risk of a cash transaction.
The person I recommended lives from doing this since 2012 or so. He simply acts like an exchange, meaning that he buys from you and sells to me, this is how he manages to buy / sell any kind of amounts. During a decade since he is doing this business he made a big clientele, thus he always has someone in the queue for meeting him to sell him crypto or to buy from him crypto.
So he acts like an exchange, except that deals with him are anonymous and the fees he applies are much more friendly than those used by a cash-in / cash-out ATM.
I may be wrong, but so far I did not suspect anything shady at him during the times I made dealings with him.