Interesting... ...I'm afraid I have to disagree, and warrant that perhaps YOU do not know as much about Bitcoin or cryptocurrencies as you think?
...It's simple. As with any commodity being sold and bought, there is STILL investment already, and trading within, that market, for people to make (and lose) money, even yes, after all Bitcoins have been mined - those in circulation still have value, and are a tradeable commodity...
So regardless of Bitcoin not being a tangible, physical commodity, people are STILL going to buy and sell it, even after all coins are mined. As far as I understand, an inability to mine new coins does not dictate the death of the currency?
In this respect, YES, it will essentially be tradeable as a normal 'finite' supply commodity, for all intents and purposes. It still holds value because there is investment and wealth within the eco-system, people are holding X amount in value of Bitcoin, and people will sell (either at loss, or gain) every day, the exact same way that people trade in finite stock market assets...
Even now, more bitcoins do not need to be mined, for me to trade (and profit from trading it), so why would that stop? - one investor makes a bad call, another profits - it's the way of all investment markets, regardless of having more supply or not...
...and yes, NOTHING is tangible/actual liquidity until you actually sell it, even company stocks and shares, and the same goes for Bitcoin. The value of the commodity, and in the 'stock' so to speak, has been injected / set by the investment level in the 'coin' since its creation.
I know enough to know that the concept in it's foreseeable future will not fly. I does not scale up, it cannot scale up. It has no intrinsic value if used as intended. There is only the bigger fool snowball value. You buy it, because you think you can sell it to a bigger fool. Do not get me wrong, this could work for decades.
The use as intended is to actually pay with the stuff. That was possible in the beginning. There you see the failing in scalabilty. Because after the tech was adopted and people started really using it, even trading it as a commodity, it became literally unusable for it's intended purpose. Decentral money.
The reason it became unusable were and are twofold. The high volatile value due to the commodity trading. And the more important fact that as a crypto currency you have to do crypto and that cannot be cheap. If it were cheap in computation time, it would not be crypto, it would not be safe, you could misuse the decentral design and forge all you want. You need 51% of the computation power in the net to cheat. That is the safe guard. But this very safe guard makes it prohibitve to use. I have to pay for power and hardware to compute for a transaction. For regular money that costs less than a cent. The additional costs are insurance and other stuff and because banks are too pricy. For a crypto currency that costs an ever growing amount of power. The more users you have, the more. You could fine tune, even by orders of magnitude, but a single transaction in bitcoin 3 years ago cost the then power cost of 300 €. I do not know the current price estimates. That costs are not payed directly of course. It is hidden in the commodity trading.
Bitcoin will collapse if the coins are mined. The design of the currency actually had the end of mining in mind, so transaction costs are payed inside the system. You do not mine the new coins, you mine the transactions in a sense, and get payed for that. But think about it, if no one actually uses the currency as a currency, but only as a virtual commodity, the system is dead. Asfarisiknow, if less people do the mining, you also need less computation power. That would be good ... but it would also come with the security risk. If you only need a fraction of the power, you can corrupt the whole system easily.
And a quite big risk is the outright ban of the stuff. Because, at the end of the day, having a thing like bitcoin is like having proof of ownership of a certificate of how much energy you wasted on hot air. Literally. If you have the coin, it is you who paid for the electrical bill. Countries are trying to get green. Adoption of crypto is the opposite. If we can ban ivory, we can ban crypto. And at least the mining of bitcoin is banned in some countrys.
Another risk is the meta inflation. How many "coins" are there currently? It feels like a new one is invented daily.
(Stocks have an intrinsic value or rather, a reason why some people want them. One is voting power in the company. The other is the money you get each year from the shares from the company. If you have no primal users, you cannot have the parasitic trade market. Bitcoin has no primal users. Not anymore. This fact just has not cought up yet to the people trading in it. There are enough people advocating it naivly or with ill intent.)