There's no methodology anyone can show you, that's why they never show their numbers.
Bitcoin is an asset like any other, there's no math I can do that will prove to you that someone can't just arrive tomorrow and buy this rock off of me for $2. And there's no math someone can do that can prove someone else won't show up the next day and offer $2 trillions for it, specially because their math can't predict inflation, or they'd be billionnaires on the futures market very quickly instead of showing off their math claims online.
Bitcoin is an asset like any other, there's no math I can do that will prove to you that someone can't just arrive tomorrow and buy this rock off of me for $2. And there's no math someone can do that can prove someone else won't show up the next day and offer $2 trillions for it, specially because their math can't predict inflation, or they'd be billionnaires on the futures market very quickly instead of showing off their math claims online.