Don't build single outpost systems then, fully develop your system and you may get to 5mil.I received the weekly payout for having a system colonized, I only have one outpost. I was not expecting some elaborate payout, but seriously...15,309 credits? That doesn't even cover the cost of fuel it took to build the thing.
I don't know what the number for a single outpost in a single system should be, but it's not 15,309 credits. 100k Credits feels more appropriate? I don't know how much tax they plan on taking away once you hit 5mil, but it shows how many single outpost systems you need to build to even begin to hit that amount.
All this building single outpost systems and then moving on is just locking other folks out of systems that may have developed them into something worthwhile.