This doesn't usually work in authoritarian countries with well functioning secret services. Economic situation in North Korea is much worse and I would not expect an uprising there.
Well, the secret service people also have their families to feed. Discontent and disloyalty will eventually make their way up.
I've read a scientific text where the liquidity/holding cost of power is "guard labor", effectively a portion of the population is willing to work for the authoritarian ruler for money but this can only buy so much time. As the country becomes more unstable the need for guard labor increases until it reaches a critical point where the guard labor is powerful enough not only to suppress the rest of the country but also the authoritarian ruler himself leading to a classic military coup.
This begs the question if Putin's secret service is well functioning.