Well, in the US, Trump's approval rating is somewhere around a record low.  People don't like what he's doing - e.g. slashing education and health spending and spending an extra £50bn a year on arms - presumably preparing to start World War 3.  This is completely at odds with what he claimed to stand for - looking after everyone, getting less involved in wars.  But, despite having to put up with him for 4 years, at least they can give him the boot and get someone else in.

The general principle is that politicians are allowed to carry on for longer if they do what pleases the majority of the people.  It's not complicated, it's democracy.  Yes, the odd outright liar and conman gets through the net, but they get booted out later.

I've got no intentions of getting involved in politics myself, but I feel that it's essential that each one of us has the power to be heard, at the polling station at the very least.  Who elected the EU President?  I've no idea, but I wasn't asked to vote on it.  Even if he's the best person in the world and is nothing but sweetness and light I demand, as a citizen, to have a say in who it should be, and therefore to hold them accountable for their actions the next time I'm asked.