The answer is very simple: anyone that rises against the government is taken out of the picture by the army and the legal system, both controlled by Maduro. And the reason for that is also quite simple: the top brass in the Venezuelan army and the legal system will be prosecuted for drug trafficking, human rights violations and/or corruption once Maduro is out; much the same as Maduro himself. All the army officers that would bring Maduro down to stop the disater Maduro brough to the country are in Jail or under 24/7 surveillance by the Venezuelan and Cuban secret services and put in jail as soon as they government has any indication they are "conspiring"against the government.

The option for both Maduro and the army's top brass is exile in Cuba or the jail, and they are delaying both as much as they can.