Kids started watching each other play games, and one of things was D&D.
Stranger Things showcased the characters' D&D campaign as a major theme from Season 1. People doing it on TV suddenly made it not just for nerds anymore.
Critical Role did a very good job with their youtube show, and having celebrities come on was a great idea too. What's funny is that posers criticized legitimate D&D players for failing to play just like Critical Role to such a degree that Matt Mercer himself had to publicly make a statement against it.
So, it looks like several important things happened in relatively quick succession:
1. D&D 5e comes out in 2014.
2. Critical Role comes out in 2015.
3. Stranger Things airs in 2016 and becomes a very highly rated show, with 1.2 billion total views as of this year.
5e coming out, that only matters to people already playing D&D. But, Critical Role showed cool talented professional voice actors having fun playing D&D to millions of people online, then Stranger Things showed D&D in an interesting positive light to millions of viewers out in TV Land.
Notice how Pathfinder was D&D before D&D 5e was D&D, but nobody was playing "Pathfinder" on Critical Role or Stranger Things, so it didn't get any benefit.
there was a young persons group and an mature persons group.
Of course, because twentysomethings and older don't want to listen to the nonsense.
there's another big strike against Traveller. Space fiction is a ghetto.
True. The franchises in the public imagination are Star Trek, Star Wars, and to a much lesser extent, Firefly.
So, IMO, the only thing that is practical for Mongoose to do is hire talented mediagenic voice actors or regular actors who love gaming to do a Traveller campaign podcast. Show millions of people out there in Internet Land cool mediagenic people having fun playing Traveller. If the podcast does well enough, Mongoose can hire a reputable competent professional screenwriter to create a screenplay for a high quality Traveller movie or show and pitch it to Netflix or Amazon Prime (no low budget piece of crap). In this way Mongoose can hook up its own crank to the wheels of fate and turn them.