This also means you need effort to collect your taxes which is another way to create impedius on infinite wealth. If you own 100 worlds, you'd need to either spend a lot of time farming them every day or two (which would be less profitable than mining anyway), OR you farm a few a day on a schedule and lets them stockpile, but ppl who let them stockpile become VERY juicy targets which makes for a great incentive for war.
Let's say each world makes 1 mil $/day, and you have 100 worlds, and you have a monthly schedule were you hit a few worlds every day. That is $30mil per world which is a few times more efficient than mining or stick shop trading, but it comes with greater risk. If another faction looks at the map and sees that you own 30 sectors, they will likely decided to raid the hell out of you, so they could make off with $1.5 billion credits by hitting all your worlds at once (about the value of an average 400k battle-cruiser), and destroy all of your claims which would take a lot of time to re-establish and rebuild their wealth.
Instead, the incentive would be to claim a small territory with the most amount of worlds so as not to draw attention to yourself. With 10 worlds across 3 sectors, your faction won't stand out on the map, and you could let them stockpile more safely. Then you just go out once a month an hit all of them for a free $300mil credits. At this rate of income, it would not replace mining, but make sure you always have the cash on hand to fill those random needs to keep your economy functional.