When I read the title, I thought you were asking us why it is valuable but I see that you are rather telling us why it is valuable. I don't know where you get your example from, but the only thing you are right about is the 21 million limit. It is as simple as that it is the best digital system to store and transfer value, especially in large quantities, decentralized, autonomous and resistant to censorship.
Bitcoins are valuable and most liked by the masses are due to it’s decentralised nature.
Yes i do agree on the fact that it has more benefits, but due to the anonymity and decentralised nature, it’s very popular among all the section of masses.
Moreover it’s limited supply also make it valuable, as when the time passes, it’s value will increase and definitely for that reason the price will also increase.
So yes Bitcoins are so far the best digital currency, and for these reasons it’s the valuable one too.