North Korea is a poverty-ridden hellhole because its ruling dynasty is a repressive, Communist tyranny, and will not allow anyone the marginal bits of freedom needed to rise to even a late 18th century standard of living. They could rise to at least a Chinese standard of living if the Kim regime would just take its boot off people's necks once a week.
Putin's not exactly the world's friendliest, most easygoing autocrat, but he's not a Kim or a Castro. Cutting Russia off from the EU or the USA is going to be disruptive, but there is in the end not a single crucially important trade good or natural resource we can deny them.