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.
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.