I am reminded of the top Super Mario players all congregating for a run on GDQ, only for a complete random fan to come to them and ask "So... if you were all stuck trying to optimize this one pipelfor over half a decade... Why didn't any of you just do the Devil's Spell?"
To which the speedrunner's reaction is: "Wtf is the Devil's Spell".
It happened to be a trick that was documented nearly 2 decades prior.
So they are red teamers :p
Which ironically is more like pentesting than VR.
You tend to have certain people who are more interested in glitch finding and spend most of their focus on that over actually running the game. Then you have TAS runners (often overlap with glitch hunters) who make TAS-only runs to determine what the absolute limit is in a game. Finally, you have the remaining 95% of the community, runners grinding the game over and over.
Strategies from TAS often are repurposed by speedrunners, perhaps most famously in Mario 1 any%, where several strats used by top runners were once considered infeasible for humans.