If you have a majority of your cost of living expenses in another currency than Bitcoin - then you should measure your profits and losses in that currency.
Yes - if you happen to know the future value of that currency, at the moment you are planning to spend it. Say, if you are planning to retire in 30 years somewhere in the Caribbean, and Bitcoin is a part of your retirement portfolio, it makes perfect sense to measure your profits in future value of East Caribbean dollar, if it is still around at that time. The thing is, you don't know it. You can probably assume East Caribbean dollar is still around, and its value would be 50% of what it is now. But that's just as illogical as assuming Bitcoin would be the world reserve currency in 30 years. East Carribean dollar is pegged to the US dollar. The US, in its present form, is very unlikely to survive for another 30 years. Hyperinflation is very likely to happen in the nearest 10 years. You don't know a thing about the future.
bulls without logic. The kind of person who thinks BTC will hit $1,000 or $100,000.
It's not that difficult to imagine $100,000,000 bills in circulation, in 30 years' time frame. As long as Bitcoin does not disappear completely, $100,000 / bitcoin does not seem that far-fetched. Maybe not $100,000 in the present value of the dollar.