HUMOR Rey Saved The Galaxy With One Simple Trick!

This, like the whole "we can't shoot at the escape pods, there are no life signs" moment in A New Hope, ended up being the fulcrum for the entirety of the rest of TFA's plot. If Rey sold BB-8, then Luke would have died, and because Finn would have never made it off of the planet, Starkiller Base would have destroyed more worlds.

Also worth considering: Luke was being selfless, too, even if that wasn't his end goal. One of the reasons he went off into the Unknown Regions is because Starkiller Base itself was going to target whatever planet he was on as soon as they learned where it was. Therefore, Luke would be putting millions of lives at risk if he pulled an Obi-Wan and lived as a hermit on a populated world. So theoretically, he's free to leave the planet whenever he wants to. He obviously won't, since the planet he found has the First Jedi Temple on it, but there is a selfless reason for him going into hiding.