[mindcandy]

From what I understand, the US Dollar is backed by: The IRS requires taxes be paid in dollars. It's a federal offense to refuse payment in dollars for purchases under US jurisdiction. The US has negotiated other countries to require payment in dollars for oil and maybe other goods. The world generally has confidence in the dollar as a fairly stable currency that is unlikely to collapse.

What did I miss?

My understanding of what backs Bitcoin is: By mining Bitcoin, you are provably putting yourself into a financial loss and therefore are provably motivated to turn that around into a profit. Buying Bitcoin is also equivalent to mining in this regard. That means around the world, millions of people are motivated to the tune of nearly a trillion dollars to ensure that the system continues to not only keep working, but grow more valuable.

[friend_and_foe]

Well, the mining stuff has a role, but in reality, the thing that backs bitcoin is the same thing that backs gold. What backs gold? You might say, that's a silly question, gold is just gold. But why then is it valuable? The answer is it's scarcity. The same is true of bitcoin.

Gold mining is destructive and incurs an energy expenditure. Economically, it incurs a capital expenditure and a venture must demonstrate a risk profile, a probability of return justifying the venture. The two endeavors have similar profiles, with bitcoin though the amount you can mine is predetermined. In gold, it is soft predetermined in that it is known generally that it gets more difficult over time to extract and more expenditure is needed, more powerful techniques must be developed. In the bitcoin world this is straightforward, "more powerful techniques" are just more transistors per square inch configured to hash SHA256. The "more difficult over time" is just competition with people who have already developed more efficient machines. Capital expenditure is pure energy, not digging pits or pumping solvents or electrolytes into veins. And scarcity is absolute.

[angry_albatross]

I think that is a fine description of the backing of the US Dollar.

For Bitcoin though, it sounds like you are defending Bitcoin as an investment, which I don't agree with. Unlike Bitcoin, the US Dollar is not considered an investment. It's just a currency, a medium of exchange. It loses some value over time, and we're ok with that. Bitcoin is pretty difficult to use as a currency, so people usually promote it as an investment instead.

Here is what I have to say about it as an investment: where is the money actually coming from for the returns? In order for the price to keep going up, people have to keep adding more money to the pool. This is pretty clearly a negative sum game, where the players on average must lose more than they win. Some people may win, but they are mathematically in the minority. Most people who appear to be winning are only winning on paper right now. If everyone who was currently holding tried to withdraw their money and cash out, who would be the ones buying them out? It's not clear. There is no utility to the thing that they own. It's essentially just a number in a spreadsheet.

[kraftman]

> That means around the world, millions of people are motivated to the tune of nearly a trillion dollars to ensure that the system continues to not only keep working, but grow more valuable.

I guess I'm asking why this isnt valuable? It seems like a large portion of the world has agreed to trade assets in USD and assign various values of there assets to the value of USD, and much smaller portion of the world has agreed to do the same with BTC, so the differences is that you have to pay your taxes with one and you dont with the other?