Ah, assumptions. Such a handy tool to back up some claims. Reality is tough, let's make an assumption with a figure that proves our point.
Example from life - my last two days.
Having over 220M I decided to buy FDL. A-rated FSD, D-rated rest, smallest PP and cargo build with shields. No weapons (playing in Mobius, tho all non combat ships are weaponless). Current rebuy of hat build is slightly over 2.2M. After all purchases Iąm left with 186M. Pfft, 2.2M when you have 186, you may say. Well, I play to increase my wealth so I can afford better ships and equipment, not to blow credits for rebuys. So I set that 186M as a bottom line and will see how fast I can recover.
With 2.2M rebuy cost in mind I started doing delivery missions. Let's see how fast I can earn my rebuy. Two days ago I earned 1.5M, yesterday I got about 800k. About 2.3M in total, for two evenings of lazy delivering. Many stations I visit I'm allied with, yet missions are in 30-60k range. Math is simple, my chosen way of life requires two full evenings for a single rebuy of FDL. At this rate, covering my FDL purchase will be done in just under a month.
Now - any single mishap, failed interdiction escape, is a major drawback. Single rebuy is two evenings wasted.
and here I'm pirating megaships.. say what again about earnings?