How many believers in democracy would let their own life be decided by a majority vote of other people?

That seems like a strawman. Most western democracies have substantial antimajoritarian components to their basic laws. Procedurally, most countries have judicial review of legislative acts. Substantive examples (from the United States) include the First Amendment (freedom of speech) and the Fourth Amendment (protection against unreasonable searches and seizures).

In other words, proponents of democratic government don't intend to communicate that they want every decision made by the majority of the citizens.