Of course a druged out population means less work done which means less money in the pockets of citizens. Hmmmmm? I am not a financial planner.

If the empire embraced the skooma trade they would gain a few things. Less people in prison meaning less to feed/take care of. Buildings would rise for storage/sale meaning more rent/tax money from the buildings. Tax money from the actual sell of skooma. More jobs to manufacture/transport skooma. Over time less use of skooma, or at the least more responsible use.
Clearly you guys aren't thinking like vulture capitalists, or even like Thalmor.

Craft a the outline of a law forbidding the possession or use of Skooma, and present it (with suitable inducements) to the steward of the Emperor as if it was his idea.

Meanwhile, using your contacts, secretly aid and abet the manufacture and distribution of Skooma.

Build prisons at the expense of the Empire. Then contract with the Empire to run the prisons.

The Empire will incarcerate anybody in violation of the law, delivering to you a slave labor force to exploit. In fact, you could suggest that the Emperor call it, "the War on Skooma!"

As for the rest of the population, they'll be too doped and apathetic to realize how they're being manipulated.

You'll be swimming in pools of septims!

Thank goodness this could only happen in a fantasy game.
