Your mistake is calling it an "asset". It is no such thing. Just because there's a limited quantity of something doesn't mean its value goes up, or that it has value at all. Otherwise all the collectible plates and other crap that's sold on late TV "limited quantities, act fast!" would be selling for thousands of dollars on eBay. I'm sure fools made the same arguments you are making about rare tulip bulbs a couple centuries ago. Tell me why rare varieties of tulip bulbs, of which there are a very limited supply or in some cases only one in the world, should not even today be worth more than a bitcoin of which there are millions.
There are some suckers who current believe bitcoin has value, but it'll be a footnote in history once the hype cycle dies and bubble investors move on to the next big thing. It isn't even useful as a currency any more due to the ridiculous transaction fees - it is now only viable as such for criminals or tax evaders - the microtransaction argument people were making back in the day faded when they realized transaction fees were its Achilles heel. No one is buying cups of coffee with it anymore. Perhaps someday something that bears some resemblance to bitcoin will gain broad acceptance, but that will be because a government or some large corporation like Facebook provides backing.