I find it hard to argue against democracy because the alternatives usually do not work well or do not work for a very long period of time.
Democracy = rule of the people (literal translation)
Autocracy = rule of one person
Aristocracy = rule of the best (literal translation)
Oligarchy = rule of the few/
rich
Meritocracy = rule of people by merit (achievements/education/skills)
The problem with democracy is that it is a game you cannot win. Or to be more precise - when you think about it in terms of game theory - the winning strategy in a democracy is populism, lying and manipulation. A politician who is honest is a loser that will lose, a politician who tries to be "apolitical" is also a loser.
It's not something happening only in poor or corrupt countries - this situation plays over again and again everywhere, just in different forms. In Georgia you promise the voters they will get a 20 lari
banknote when they exit the polling station, they'll vote for you. In Hungary you promise the voters that you'll protect them from African migrants, they'll vote for you. In
Greece you promise the pensioners that they will have pensions higher than their former salaries, they'll vote for you. In Turkey you promise the voters you'll bring back the ottoman empire and they'll vote for you.
Another problem I see is that a mentally healthy and skilled person won't go into politics, perhaps at the local/municipal level at the very maximum. To get into politics, you must have some huge desire - for power, control, revenge, recognition - so at the top level, politics is full of sociopaths but those are exactly the politicians people voted for. So democracy "works" exactly as expected. And with current laws and constitutions, you cannot simply "switch" to meritocracy, dictatorship or ancap...