What you mean by “hypothetical use” vs “actual use”? In your own comment you mention nothing about “hypothetical use” yet here you talk about one, OOP also failed to mention anything about hypothetical use and only talk exclusively about unrealised gain. If unrealised gain(stock, asset, etc) is used to trade for another item, then yes, it’s already a realised gain, the tax should be levied on the item purchased or the asset sold, whichever makes sense. If the unrealised gain is used to secure a loan, then no, it shouldn’t be taxed because it’s only change hand on paper, and the loan came with interest, and you have to pay back that loan. Net worth is nothing but a dick measuring contest, taxing it makes no sense.

So no, unrealised gain shouldn’t be taxed because it’s unrealised, it’s like taxing a grocery store’s unsold item.