How are people getting hundreds of millions in the current CG, so fast?

How are the people in the top 25% getting so many credits? Is the new ship that good, or are they using some other method? Is the new ship way more powerful or particularly suited to this CG, or are they likely to be doing AFK pirate mission stacking, or something else?

I don't get a lot of time to play, admittedly, and this week life has got in the way a lot, but I would say I have spent about 5 or 6 hours in total and am still outside the 25% mark. Granted, last night, I did get several of the assassinate missions where you get there and then have to go find a contact in another system and all that rubbish wasting time, but still, the top person currently has nearly 2 billion credits from this CG already, according to Inara!