A cynical statement used to point out that no matter how stupid someone is, they can still decide the fate of a country.
There are people who actually think that an almost eighty-year-old man who can't even walk up a flight of stairs without tripping or stumbling at least three times and can't go more than five minutes without uttering a non-sequitur or having a random emotional outburst and has a long, documented history of being extremely racially prejudiced whenever it's convenient to him is fit to run an entire country. And these people can vote.