Thanks for your responses! This is the conundrum I find myself in. I think a bitcoin wallet takes some of the characteristics of an intangible as well as a tangible. Part of my argument rests on treating it like a tangible because:

(1) it can be exclusively possessed, as you pointed out ("I can transact from the UTXOs I can sign as inputs. But it's up to me when or whether I will"),

(2) ownership of it expresses a property right in it of itself, and

(3) it is alienable.

A typical intangible would be a stock certificate or a contract right. The contract and the stock certificate are physical, but they rely on the legal system to give them effect. The certificate and the contract are not the valuable part, just representations of ownership in something else.

The private key = password is analogous for the most part, but one key attribute is that the password gets you into account controlled by someone else. Social media account, bank acct, etc. They have intermediaries. The private key can be used to deprive all others of control over the wallet, making it capable of true exclusive possession.

Additionally, I could throw my key away or write it down and leave it somewhere, making it alienable. The wallet does not have to be tethered to someone.

Would love to hear your thoughts on this. Does this make sense to you? Is there a more common sense approach?