I made enough with a Booze Cruise but it's hard work and takes a long time
- load ~20kt of cheap wine and 5k Tritium. that's about 25-30 trips with a large freighter ship
- jump the carrier up to Rackham's Peak. that's a minimum of 6h jumping the carrier every 20 minutes. hope that there is a slot available in the last bottleneck system
- wait for the system to go into public holiday. it usually happens once per month but that is not guaranteed
- unload 20kt of wine within 48 hours to an outpost with one medium pad. that's about 50-70 trips in Python or Type 8 and there's always an NPC just landing on the pad when you come in
That should make about 4-6 billions in one large grind. The life of a sole trader with a large truck.
Do this and you won't want to set foot on you FC again for months.
You
will earn a heap of credits but... y'know.
Personally, I reckon the best way to earn the big bucks is just to look out for opportunities.
Most of my time, in ED, I'm just doing stuff I want to do and, honestly, I earn almost nothing.
Once in a while I like to explode stuff so I head for a Pirate POI, CNB or Hazres and spend a few hours making stuff go boom.
That earns me a few million credits and pays my FC Upkeep for a few weeks.
Once in a while a gold-rush or CG will come along that gives you an opportunity to earn the big bucks.
In the last CG, for example, I earned half a billion for hauling cargo, another half a billion for exploding criminals and then got paid a little over half a billion for doing it.
So, that 2 weeks gives me enough credits to pay for the Upkeep of my FC for 3 years.
Looking at the INARA log of my finances, it just stays the same for months after month and then, a couple of times a year, there's a bit of a spike where I earn a couple of billion credits one way or another.
You just have to keep your eyes open and take opportunities that are presented.