You bought near the top and that is always a bad idea, Im not trying to bash you or anything but you do not seem to know a lot about trading
That guy didn't do wrong, he bought BTC when it just had dropped (from a short spike, but still) 500eur.
Meanwhile a lot of people started buying, at the top, an already overpriced BCH. And these won. Call it balls or luck, but that goes against your "buy low sell high".
I hope the BCH isn't gonna kill the BTC. It's already going down right now, maybe that will push the BTC back up. Surely it made some people very rich.
Most people always make one funny silly mistake when a market is being pumped; they always end up trying their luck and then ending up as FOMOs. They are usually always the ones at the losing end anyway.
For those who could not get in at the early stage of the uprising, they could have just stayed out. Some bought the speculation thinking BCH is about gaining ground, now they have fallen for the manipulation. That is just what BCH will always keep being.