Except if you spend a night farming you get hundreds of thousans of credits from looting ... no slicing necessary. What slicing has going for it is that it's comfortable steady stream of credits. But you sacrifice self sufficiency in your crafting profession for it.
Except you can train the mission skill you miss simply on a lvl 10 alt and level it there to 400.
Slicing missions arent guaranteed its possible to get less then you spent on the mission.
Hint: those moderate, abanduant, bontiful, rich words on missions mean something.