That paper has some value if it is placed in the context of the moment and time in which it was created - that is, as some kind of message to the system, given that it appeared behind Janet Yellen while she was giving some kind of speech in front of the US Congress. For this reason, I can find justification that someone paid 16 BTC for the same, especially if that person has so much BTC that this amount does not represent any significant expenditure.

There will always be some items that will be valuable to collectors, but only their "originality" and rarity will determine their price. If someone managed to write that same message on paper and take a picture with, say, the current president of the US - would someone pay more or less for that piece of paper than the one that was recently sold?