Maybe best to reach out with their support and try to ask about what happen.
The Betfury support is very responsive; getting a response within a few minutes is certain. That will clear the doubts and provide a better answer to the question, which I think we already know the answer to.
Winning 1 ETH or an equivalent of a substantial price on the spin wheel—has that ever happened in any casino's history?
Yeah this is actually good about them since their support is very responsive.
But somehow we provably get the answer came from the insights of people so I guess we already have an idea about what happened. Also there's no proof to show so I guess what better thing to do is to move on and try to record the next spin so that we can show something if same situation happen to us.
So far upon reading this thread on daily basis I don't hear anyone saying that they win 1 ETH, but we don't know if there are people outside win such huge amount there.