I sold you the painting for 1MM(million).
then buy it back from you for 2MM.
then sold you to 3MM
buy it from you for 4MM......
at the end I sold to you for 10 MM.

so both of us made 5MM in average?
Ok now the painting got burned. it worth 0.
How much we lost? 5 MM in average? LOL

No we don't last 5hit. all we lost is the painting. it is just how is the idiots bought the painting when it got burned. and he lost probably about 5 MM. But that 5 MM did not lost. it went to the pocket of the last seller.
No money got created and no money got lost.

I have no degree in economy. But the math isn't that complicate.