My 2 cents.
I do slicing in 2 ways.
1) Send my companions on crew missions
2) While adventuring I slice everything I can find.
I have attempted to sell the mission discoveries etc I get from slicing but they don't sell that well. I only post things at the suggested price I never go above that. It may be the market is so whacked those prices are to high. I don't know.
I am still able to profit but not near as much as I was. I combine the profits from slicing, the selling of grey loot to vendors and what little I manage to sell on GTN. Its not great. If the prices of things like training for 1 sith ability wasn't over 9,000. That might help. Prices for everything is so high that my income makes it difficult for me to...
Train my Sith Abilities, Artifice recipes, Repair gear, purchase mods or new gear as old gear becomes outdated. I can only gear 1 companion and even that is behind.
Perhaps the issue isn't slicing but the cost of other things.