Once Bitcoin is in late mayority of adoption stage i think there will be no more cracy gains, it will just be a bit better than gold, keeping up with inflation. The more inflation, the more taxes you pay. So basically eg with 40% tax you are only saved from around 60% of the fiat-inflation.
Your thinking could be wrong as well. So what's the point of worrying over something that we ain't sure that it will happen. What if there are still crazy gains? Why not live in the present and allow bitcoin to sort itself out when we get to that late majority adoption stage you are talking about. And you don't even know when that stage will happen. Bitcoin is still growing, and we don't know when the late majority will happen. Bitcoin is heading towards two decades now, but it still feels like it was invented yesterday. So it might take many years or more for the stage you are talking about to happen, and who knows how many of us might be alive to witness that stage.