Okay, a bit of a summary as to why buying/holding bitcoin is terrible for the environment.
The blockchain is being calculated by every single miner in the world. The software is designed to (roughly) spit out a bitcoin every ten minutes. This is true whether there are a thousand miners or a billion. Every ten minutes. What happens is that the difficulty of the mining increases proportionately to the number of miners. But the blockchain is recalculated every ten minutes. Additional miners don't 'help' this updating, calculations still get processed regardless of the number of miners.
But, at the individual level, it's worth mining if your reward is sufficient. If I know that you're willing to pay $10k USD for my next mined coin, it's worth spending $9999.99 of electricity doing it. Especially if the servers are already set up, and now are just mining their next coin. Now, people who're super-good at business won't spend that much, because they're going to amortize the wear-and-tear on their machines and factor that in.
But other people are mining used pre-existing infrastructure. They're willing to damage their computer in order to get money, or (more likely) they don't know how to run the amortization. But every single person is willing to burn $9999.99 of assets in order to get the next bitcoin. In Edmonton, AB (using conservative statistics) this means that mining one coin is going to generate 21 tonnes of CO2 emissions. That's the average emission per Canadian per year.
And, it's even worse. In some regions of the world, electricity is subsidized. You know, because electricity is such a useful tool, it's sold at below-cost. But the miners in these regions will only care about their personal bank account. It doesn't matter how much their society spends on the electricity, they're willing to spend $9999.99. Or criminal hijackers using malware. Students hijacking school computer labs. Technicians hijacking company servers. They're willing to spend other people's hardware and electricity in order to get the next coin. Hell, I ran folding@home on work computers when I was younger, and I was just trying to be altruistic. I didn't heavily weight that I was spending someone else's money ...
So, being willing to hold a bitcoin at $10k means that you're providing a signal "the next mined coin is worth $10k". Being willing to 'buy back in' at $8k sends a signal of what that next coin is worth.
Keep in mind, all of the really great things about bitcoin don't require a high value. The Venezuelan buying toilet paper doesn't care if he's transferring 0.01 bitcoins or a thousand of them. The transaction will be conducted at what they perceive to be the very best real price. But the social cost of the bitcoin is utterly dependent on its actual value. There will still be people mining like stink if Bitcoin were worth $0.10. But only if their electricity + amortization (+ subsidy) makes it worth it.
Finally, most of bitcoin's value is maintained through a parasitical relationship with our governments. If the EU said "we will not enforce (using our courts) if the contract contains bitcoins", the value would plummet. And we wouldn't have to spend any tax dollars looking at these contracts, and chasing rabbit trails of ownership. Nada. Never mind that Venezuela would literally have more money, since one additional avenue of abusing a subsidy would be reduced.
Edit: as an aside, a similar problem is achieved by fixing a country's currency to gold. The difference being "the more gold miners there are, the more gold gets pulled up". Each increase in price is followed by an investment intended to increase supply.
