I have no idea why she decided to smuggle hash. There are warnings all around the airport about the consequences.
Griner has played several seasons in Russia during the WNBA off season since 2016. That being the case, I'm sure she(?) had some familiarity with the rules for entering the country, as well as what would and would not be tolerated while staying in Russia. My guess is that Griner thought she would be given a pass by the authorities because of her "celebrity status." That may work in the U.S., but not over there.