Exploitation

Another person emulating the suspect's username told the BBC they did so "for social media clout", adding: "People will do anything that gains them followers and some popularity."
Kelly-Leigh Cooper "Bianca Devins: The teenager whose murder was exploited for clicks"

Leaving aside for a moment the nakedly self-serving incentive for someone hoping to bring people to their social media account to find pictures of a murdered teenager to claim that "everybody does it," it does appear to be true that there's a certain amount of internet desperation to become an "influencer." It strikes me as being something along the lines of playing the lottery; while one can say that people who pin any amount of hope on the strategy are bad at math, one might also say that they're actually quite aware of their dismal chances of "making it" any other way. And if impersonating Brandon Clark online in hopes of attracting the attention of internet voyeurs has a chance of leading somewhere, there's going to be someone who sees that as the best chance available to them at the time.

And while one can make the point that people should never be in the business of seeking to better their own position through other people's incorrect desires, that horse has long fled the barn. I'm sure I'm not the only person who felt that the BBC, along with who knows however many other news organizations, could be credibly accused of exploiting Miss Devin's murder themselves. After all "teen-aged girl meets adult man and their relationship ends in tragedy" isn't exactly rare enough that it would otherwise have been considered newsworthy, let alone something that should make international headlines. One wonders how many of the internet voyeurs who went looking for pictures of Miss Devin's murder did so after they'd heard the photos were out there through a respectable news outlet.
 It may be easy, and perhaps even expected, for people to see the internet voyeurs and the people who wished to cater to them as just another basket of deplorables. After all, it's a safe bet that at least some of the people who were promising pictures and videos were simply taking advantage of a convenient internet commotion to feed their egos. But how many people were hoping to jump-start their struggling would-be social media careers or get people to their web stores in the hope that once the initial disappointment wore off, they'd stick around? I don't know how much internet desperation is actually out there for what appears to be the glamorous, wealthy and leisure-filled life of the internet famous, so I don't know to what degree this phenomenon can be considered a symptom of something that perhaps bears looking into. But to the degree that a teenager's murder can look like an opportunity that one can't afford to pass up, something's likely broken.