Everything should make sense.
If a CMDR can successfully hack the Bank of Zaonce and skim off rounding errors for a year, they could make trillions of credits and it wouldn't bother me.
However, being paid even 50k credits to move 1k worth of trash 237ls and having two days to do it is absurdly indulgent to the point of being offensive.
In general, credits are too easy to come by and the Elite economy defies reason by not taking supply and demand, nor risk vs. reward, into account for anything other than basic commodity trading, which is itself shoddily implemented. All the missions scream "this is a game!", and you can smash a million ships without your creditors/insurers ever seeing you as more of a risk than one who's never had to eject.
I'm wholly against hard caps, but if I had things my way, the game would be quite a bit more plausible, and ruthlessly so.