How does tyranny arrive and survive?

A juvenile answer is that devilish persons somehow seize the levers of power while the nation’s people are innocently going about their business. Wearing sinister smiles and twirling the tips of their moustaches in dastardly fashion, the tyrants unilaterally impose their criminal wills upon the populace.

The People soon realize that their dictators are venal and vile, but there’s little they can do other than silently submit.