How to make money without having to complete the uncompleteable missions:
Accept support missions where they give you a power regulator to go fix some settlement's power.
Make sure the regulator is in your inventory.
Abandon the mission.
Taxi hop to the next nearest station.
Go find the bartender, sell your power regulator for 100k.
Repeat and profit?
I already bought a flight suit 🙂
Your inventory space only allows for 2 regulators so you can only make 200k in each go.
edit: the taxi hop is necessary only because the regulator doesn't seem to show up for sale in the same station you picked it up from (relog didn't seem to work either)