It's a bit of time I'm asking myself this question.
Let's imagine the following situation:
A guy visits another guy to receive a payment in BTC.
He doesn't have mobile internet connection, so he asks his host to connect to his host's wi-fi.
His host, that we assume for the sake of our inquiry wants to scam his guest, connects him to a fake internet in which the real BTC blockchain was forked in order to fake a transaction that in really will never happen.
So once the first guy will go back home he'll see that his payment has disappeared.
Is this situation technically possible?
I think its possible to deceive a person using online crypto wallets. However, what you are asking about is excluded, it is checked very easily and "fake Internet" will not be able to help scammers to fake the BTC blockchain