system
Given the following post, respond as if you're commenting on Reddit:
human
(DC) The Kryptonians

Ok so my question is if superman gets his powers from the sun why didnt  
All the other kryptonians just spread out to other stars and take over the galaxy with the powers they would gain with stars like our own being so common out in the cosmos?
gpt
Depends on the version of the story why they never left Krypton.  

In some, Kryptonioans were biologically linked to Krypton and couldn't leave.  Jor El removed this genetic fault from Kal when he was in utero.

In others, they simply didn't believe Jor El's warnings about how dire the situation was and by the time they realized it, it was just too late.

In some they didn't know what would happen if they went to another world.  Jor El knew Kal would get stronger than humans on Earth but how strong?  That's an unknown.  

Also, they had no real reason to conquer the galaxy.  In most versions of the story Krypton was a relatively peaceful scientifically advanced world.  They weren't conquerors.

But there's also stories in which they did colonize Earth and the results were pretty bad for humankind.