Being "a digital currency that is not tangible" is not a reason why people won't trust it. As a matter of fact, it is worth more trusting than a piece of paper you are not certain to be genuine and which supposed to hold a certain value.
I would generally trust a piece of paper more than a string of numbers and letters associated with an otherwise anonymous cryptocurrency transaction. Why? Because a judge in a courtroom in my jurisdiction would also trust that piece of paper more than a complicated series of hash values. Capisce?
Consider that the imagined "piece of paper" will include information which identifies your purported counterparty. Just like your identity is established in the blockchain when you... oh wait, no it's not. So by default, you are in a more legally favorable position as compared with a seller when the transaction is recorded on the blockchain. Given this asymmetry, any rational seller will charge a premium in exchange for your anonymity (as any rational economist would agree), and in recognition of the non-reversible nature of your trade. In accordance with this, the seller will endeavor to limit your rights as much as possible given the risks associated with trading with an anonymous actor on a given blockchain. Your ability to contest such limitations is contingent on your ability to legally contradict representations made by the seller. The seller is not legally required to affirmatively explain to you in full detail any rights which may or may not accrue to you in the event of a sale.
The piece of paper, on the other hand, is a bona fide legal instrument which grants its holder specific rights which do not require any special adjudication. The entailed rights and responsibilities are by definition explained within the "piece of paper".
Note that while you may claim that the piece of paper described above is not confirmably geniune, you must similarly acknowledge that the concordant NFT you hold may not be genuine. (If you are not aware that NFTs may be forged, then you should immediately stop trading NFTs until you have acquired a genuine understanding of the mechanisms which underlie NFTs). You should similarly note that the "store of value" you appear to believe to be inherent in a given instrument is in fact not present, except in the eyes of a prospective buyer. Consider that this buyer might be aware of the controlling dynamics described herein and may be more interested in the "piece of paper" than the less legally secure NFT.
In terms of legality, go ahead with your piece of paper; it's warranted by the government itself. Your bill is a legal tender, your land title is a legal piece of proof of ownership, and so on. If your trust is based on what is legal, then trust all of them.
As for me, a string of numbers which, together, makes a system which is next to impossible to tamper is more worth trusting than a piece of paper which is only valuable because the legal powers say so.
Trust on pieces of paper has always been broken and betrayed. On the other hand, you cannot cheat against hard-coded numbers.
