How can you vandalise something that is rubbish to begin with

I'm increasingly coming to believe that artists, art collectors and art critics inhabit a different world from the rest of us.

Above is a painting by Mark Rothko which is reckoned to have a value of £50 million.
It was innocently hanging in the Tate Modern (where else?) when it was allegedly vandalised by a looney called Vladimir Umanets who daubed his name on it in black paint in the name of "Yellowism" But why not in yellow? Well I said he was a looney.
He has said that there are precedents for artists signing other artist's work and cites Damien Hirst as an example. He's got a point there!

This is how Vladimir describes Yellowism:

Yellowism is not art, and Yellowism isn’t anti-art. It’s an element of contemporary visual culture. It’s not an artistic movement.
It’s not art, it’s not reality, it’s just Yellowism. It can’t be presented in a gallery of art, it can be presented only in a Yellowistic chambers

Strangely, if I close my eyes and concentrate really hard I can almost get what he means. I think he's saying that yellow is a colour!
Whatever. He's now been charged with vandalising the above work. Apparently it took the police a couple of days to actually serve the warrant so it seems they had trouble deciding if he actually vandalised anything.

But all that is beside the point really. I cannot see how this painting called Black On Maroon can possibly be worth £50 million.
Below is my take on it:

It took me about 2 minutes with Photoshop but if somebody wants to give me a few quid I could do them something in paint and canvas to hang on their wall in a few hours.

Maybe a Mark Rothko is worth £50 million because he's dead. Well frankly all this arty farty crap makes me feel so depressed that I can't rule out suicide myself!