That graph shows that bitcoin merchants services went to a volume from pre 2017. That looks so strange to me, because there is so much more interest for Bitcoin then it was in 2016.
It all comes down to the type of interest. It's clear that the majority of the people that came in last year only care about their gains and don't even think about crypto currencies as in them being money. It's nothing more than a speculative toy for them, which is unfortunate but we can't do anything about it. 2017 has been the year of the ICO's and they brainwashed people to such degree that there is nothing useful that they contribute to. They hop from token to token in an attempt to catch the next 10x increase. Good thing is that the ICO hype is slowly fading and with some luck we'll get rid of these idiots within a year or two....