*facepalm* Ok, one by one...
It's "rarity" will not be reached until 2140? aka we will all be dead before all the bitcoins are mined.
Yep, 21million bitcoins that will not be mined till 2140.
I will be dead long before Bitcoins are actually rare.
Bitcoin is rare at every point in time between now and 2140. Right now, no more than X bitcoins can exist. Period. Tomorrow, no more than X+3,600 bitcoins can exist. Period. Their supply is constrained, and thus they are rare, unlike, say, USD that can theoretically have an unlimited supply and created in any arbitrary amount at any point in time.
Using your claim, I can say that gold is not rare, and its "rarity" will not be reached until all the gold in our solar system is mined, which will likely be beyond 2140.
No, Gold is used because unlike iron it will not rust.
Unlike copper Gold will not turn your finger green.
Gold makes better jewelery that lasts longer.
Plenty of metals do not rust, do not turn fingers green, and last for a very long time. Like Aluminum for example. Or brass. The only reason gold is worth more than those other metals is because it is rare, aka limited in supply.
Likewise, Bitcoin is used because it is decentralized
Unlike fiat, bitcoin has no counterparty risk
Bitcoin makes better money, because it is not based on debt, and can be programmed to do things money by itself can't.
Where can I spend a BTC?
At over 20,000 different merchants. Thanks to services like Gyft, that even includes Amazon and Target, where you can buy almost anything you need.
Can I buy a burger for BTC?
Yep. From Burger King, Red Robin, Applebees, TGI Fridays, and directly for a bunch of restaurants around the world.
Can I trade a BTC for a beer?
Yep. There are plenty of bars around the world that accept bitcoin directly. One just started taking them in Baltimore just two weeks ago.
On the other hand I could easily trade a gold necklace for a keg,
Or a few bags of burgers.
Walk into a Burger King, and give them this proposition. IF they do take your gold, chances are you will severely overpay for those things, compared to gold's actual exchange rate. If only because it's a pain in the butt to convert gold back to fiat. Higher chance that they will tell you to go away, because they don't have the equipment to check whether your gold necklace is made of real gold.
Right, It has a bunch of nice qualities for a currency, and nothing you can spend that currency on.
At the moment you can basically buy drugs with bitcoins or gamble with bitcoins.
And this is why you fail so embarasingly bad. You are making the typical mistake of looking at bitcoin as a funny internet currency, and are not even bothering to look at where it can be spent, let alone what it can actually do.
First of all, at the moment, I can basically live off of bitcoin entirely, and aside from having to use my credit card for gas, I actually do, as do many other people. And second, bitcoin is not a "currency," it's a globally distributed asset ledger. We can use bitcoin coins as currency, or we can use bitcoin coins as tokens to represent something else. Think of ANYTHING that requires proof of ownership representing an asset. Title to a house or a car, gold backed currency, commodity ETFs, stocks, bonds, you name it. All of that can be linked to a fraction of a bitcoin, and be traded on the blockchain directly, making the jobs of notaries, trust lawyers, title storage services, investment banks, brokerages, and many other financial system jobs obsolete. Until you realize this, you don't understand what bitcoin even is, let alone what it is worth.
