Democracy is and always has been completely dependent on voters taking the time and trouble to properly inform themselves about the people and policies they are voting for. If they can't be bothered to do that, if they're happy to swallow even the most blatant and transparent of lies provided they agree with their prejudices, they can be easily manipulated into voting against their own best interests, and in the interests of the people doing the manipulating. That's when democracy fails.
Enough voters now seem to live in a self-imposed bubble of ignorance, prejudice and misinformation for democracy to be failing worldwide. The problem is most acute in the US, but it's not unique to it. In my country ignorant, bigoted voters expelled their own country from the world's largest free trade area. In democracies all over the world willfully ignorant voters are blaming the most powerless and harmless sections of their population for the problems in their lives, most of which are actually caused by the most powerful and dangerous, and voting accordingly . Democracy is now the problem, rather than the solution.
At 71 I can only be grateful that I never had children, and hope that I don't live long enough to see the worst of what's coming.