> And that's not necessarily true. It assumes that everyone mines bitcoin for the purpose of obtaining bitcoin, not to support the network.

Like someone is intentionally donating money in hardware and electricity in order to support the project? How many dollars a month would you personally spend to do this? Maybe there's some rich people involved who have the money to spare? At the current cost of mining, how many dollars a month are are required to keep the economy going (I have no idea), and would it be possible to get that much as "charity" donations to support the bitcoin project (I have no idea either)?

If the Bitcoin network is valuable to someone, they would likely invest to keep it running and secure. I would be more than willing to pay to run my mining equipment (bought with previously-mined bitcoins, about $1/day to run) to keep the network up.

Speculation has driven the cost of mining way up, but the speculation isn't inherent to mining. If the network was run entirely on a "charity" basis, the costs to mine would be much, much lower.