This is an interesting one.
It looks like it can be done but I don't know exactly how.
I guess traders should be careful of "fake internet" then or even avoid exchanging Bitcoin via public Wi-Fi or other people's internet.
Imagine if this is done on a large scale by a powerful entity.
TBH from this discussion it seems like it can't be done or at least the cost of doing it would be much higher than just buying the BTCs