Regardless of the pros/cons of the war on drugs, I can definitely see why this would be super fun to work on as an investigator. It's an incredibly complex problem to identify someone who is using all available technology to remain anonymous. And once you actually found them, I imagine that you'd be pretty excited about it.

The part where he paid $40k to kill that person for knowing him seems less fun.

Some people[1] think drugs are bad, and want to stop people selling drugs.

Some people think the other stuff sold on SR is bad, and want to stop people selling that other stuff.

Some people just want criminals to pay the tax.

[1] I strongly think that legalising drugs, and treating them as a public health not criminal justice issue would help a lot.

Because you're a law enforcement officer, and it's the law?

Sure, it's a dumb law, but if you choose a career as a LEO you're not signing up to decide what the laws are. That's the legislature's job. Your job is to enforce the dumb ones along with the smart ones.

It's like the scene at the end of The Untouchables, after we've watched Eliot Ness throw everything he has into fighting bootleggers for two hours. Someone runs up to him waving a newspaper announcing that Prohibition has been repealed and asks him what he's going to do now. And he looks at the paper and replies "I'm going to have a drink."