The “true” value of Bitcoin depends on its future use case. If users would, en masse, lose interest, then it could end at zero. On the other hand, in the unlikely scenario that Bitcoin takes over all worldwide payments, its value could rise beyond $1mln.
If Bitcoin is failing as a payment system, and is now primarily used as an asset to hold, the only remaining justification for investing in Bitcoin is the assumption that others are willing to buy Bitcoin at higher prices in the future.