|YOU'VE FORGOTTEN YOUR PURPOSE!
Some Scientists were unwillingly forced by Aku to create robot armies and evil technology. Those scientists no longer wished to serve Aku and planned to escape Earth. Thanks to Samurai Jack, their attempt was successful (Episode V: Jack in Space).
It was unknown how Aku's destruction in the past affected their careers, since there was no Aku to order them to make robotic servants for him, not to mention their own existence, in the future.
The Scientists were said to have created the Beetle Drones as an "upgrade" from the X-Model assassin robots, however, X-49 (correctly) believed them to be inferior to the X-series (Episode L: Tale of X-49).
In exchange for their technical services, Aku provided them with resources and materials to create his robot army and henchmen.
A massive army of their Beetle Drones were single-handedly slain by Jack in one of his most heroic efforts; that was one of the only times that the Beetle Drones were nearly effective in killing Jack (Episode III: The First Fight).
Later, despite having fifty years to perfect their designs, their robots were still just a minor inconvenience to Jack, when Jack used his electronic polearm to impale their largest and most powerful beetle drone to date, only for it to explode without landing a single hit on Jack (Episode XCIII).
The drones were likely erased from existence after Aku's destruction in the past.
In " The Tale of X-49," the scientists were seen perfecting the design that would become the X-series of assassin robots. One scientist installed an experimental "emotion chip" inside of the robot X-49, which caused him to outlive the rest of the X-series, only to be destroyed by Jack due to his emotional hubris.
They were likely erased from existence after Aku's destruction in the past.