He didn't use him though?
Sawaragi did sell drugs but he didn't use Izumi to sell it, he just made it seems like he used him so Izumi will hate him, the old man who he gave the coffee bag to did not do drugs, which means that the small drug bag he found in the end was just to mislead him to hating Sawaragi who is actually such a sweet character who deserves the love :'D
Then the people who are put in jail because they became addicted to opioid after using them to get rid of chronic pain because the legal drugs didn't cut it didn't have their families ruined? Oops?
The only thing I didn't like was how lightly Izumi treated the whole drug trafficking thing with Sawaragi. Instead of "Waaahh, I didn't know he used me to pass off drugs and now he's going to jail, but I'll wait for him," he should have been super-pissed that Sawaragi used him like that. Not to mention the fact that drugs are a seriously dangerous substance, ruining peoples' lives.