"Donald Trump is proof democracy doesn't work". Agree/dis/why?

Depends on which side of the fence you're on. If you voted for him, it does prove it. If you didn't vote for him ten you will see it as not working. 

I agree in a way.

The fact that only an independently wealthy celebrity can significantly change the status quo is proof that democracy hasn't worked for a very long time.

Usually the establishment picks winners and losers simply by controlling how much funding and positive press they get. Usually they are able to make sure that nobody they don't control has any chance of winning. 

You should be able to see past your hatred of Trump and realize that he is an avatar for a mass movement. That is democracy functioning even if you don't like the result.

i think its true

Nope ... I disagree.

Why?  Because the American President is not elected via democratic means.  

Trump is evidence that the Electoral College worked.
But the Electoral College is not based on democratic election results.  If it were, it would give votes based on a ratio of popular votes ... rather than "winner take all" as most states do it.  The very fact that 3rd Party candidates seldom receive Electoral College votes, is proof that democracy does not enter in to the equation.

But taken on a whole, democracy does not work on any large scale.
"Mob rule" is basic democracy in action.  The majority rules, and will exploit the minority.
That is why a Republic is needed.  To place limits on the majority, and protect the minority.
But even a Republic can be corrupted, when the people refuse to control their representatives - as America has failed to do for generations.