It seems about right for the time invested, at Tycoon rank, I can make about 40 million in the same time on passenger missions, or certain CG's. Sothis is not an exploit, but they could do with the mission cargoes being a bit more varied and unique. No one would pay that for biowaste. There are still payments of about 10 million for say 6 tons of biowaste, which is absolutely stupid, especially when sitting next to a 1 million mission for 60 tons of the stuff. They should have proper mechanics for long range missions, not happy side effects.