I sincerely wish Bitcoins were truly fungible but clearly they aren't (yet). The growing toolset of taint analysis makes this obvious. Mixing services help a ton but are at risk. If Bitcoin is fungible then how do we know which are in Satoshi's stash? No, fungibility is an illusion for now.
u may know your maths but here is some fundementals of economy
intrinsic. that is a buzz word for the commodities market (meat, wheat, oil gold).. not the asset/currency market. though gold is both an asset and commodity. the buzzword intrinsic should be only used in the context of commodity. EG its the golds intrinsic commodity attributes that makes it a good asset.. but never its intrinsic asset value that makes it a good commodity
fungibility: has nothing to do with knowing who owns what..
eg donald trumps bank notes in his safety deposit box are no different then bill gates's,
eg a $10 in the cash register at starbucks has no different value then a $10 in mcdonalds..
fungibility is not about knowing who owns it or where it currently sits.
even a drug dealers $12,000 illicit stash that they cross the border with, is still the same as the $12,000 value that eventually is handed out to officers for christmas bonus/retirement funds
fungibility is about messing with/ treating one as good and one as bad.. EG accept this coin because X destroy that coin because Y.
moving funds due to hacks/thefts/bad management/mistakes/government seizure. does not affect fungibility.. because eventually they are put back into circulation. but destroying funds out of circulation without replacing an equal amount. is bad
50btc in satoshi's addresses has no fungible difference to 50btc in coinbase. or 50btc in my address... 50btc is 50btc... and thats how it should remain.