I knew I shouldn't have checked my phone....
Cake analogy - if you bake another, I don't get less as a result - agreed - but the creation of another cake devalued the first slightly (but increases the value of flour and eggs because there are less of them, and you are down by the cost of the ingredients.
Painting analogy - wealth hasn't been created, the value of the component parts has fluctuated IF, someone else pays you more for it. It's similar to a profit 'on paper'.
The cat site analogy - throughout the whole scenario as described, no wealth has been created. Money has moved around. People have paid money to see pictures of cats...not a commodity. And the £50m we've got is just a balance on a screen until we spend it. Buy a Ferrari each and we're just transferring money for a (usually) depreciating asset. None of which is affecting the global money supply or debt, or global wealth.
Couple of analogies for you.
You buy a house for £100k in cash - in 10 years it's worth £150k. Have you created wealth? No, because the replacement cost is the same.
If you bought it with a mortgage, you've paid £70k out and still owe £50k, meanwhile the replacement cost is still £150k - you're £20k down at this point. The bank is £20k up at this point, they've had £70k and still owns half your house ( but holds full title).
Next, you're in China, and all you have is a £50 note. Nowhere accepts Sterling - you effectively have nothing.
Cash doesnt necessarily equate to wealth.
There is a finite amount of wealth on the planet, the value of which fluctuates, but mostly increases, which decreases the value of the money that buys it. But all the while, the money in circulation is never enough to pay off what is owed.