If bitcoin's benefits do not offset the "massive costs" for you (because you're likely coming from a first-world country), it doesn't mean that these benefits do not exist for people who were not so lucky as you are.
Carbon pollution is not just a one-time cost, it is a debt that carries a massive interest rate with it that will be paid for generations. So whatever benefits someone else might reap from Bitcoin, it certainly isn't worth it to me.
People use way more energy for dumb heating. In my region humans can't survive in winter without it. There is no reason why mining rigs can't be used for 'smart' heating, heat being a byproduct of mining.
It is not done currently only because the energy use of bitcoin is so miniscule compared to other uses, that it's not even worthy to bother yet. Down the road, it'll likely change, but currently complaints about 'massive costs to the environment' are mostly virtue signalling.
If the energy use of bitcoin was minuscule while heating a building, and it could generate mining rewards while doing so, then people would be using it for that purpose. They aren't.
That's my point. It's not popular because it's not economically viable in many cases. So heating buildings is another thing that Bitcoin is supposed to improve, except it really doesn't.
Why do you think it would be less economically viable to use mining for rewards + heating rather than just rewards? It's both economically advantageous and arguably slightly less pollutive to offset energy consumption used for heating.
Because professional Bitcoin miners--the ones who are actually getting rewards--are not using rigs in their homes. They make more money by using industrial-level setups, buildings dedicated to mining that are located where the energy, taxes, laws, etc. are most favorable. These miners are the ones making the actual money from Bitcoin, not the hobbyists running a home rig who never mine a single block before their hardware is ruined. Home rigs do not compete with industrial setups on cost, not even when taking heating into account.
"Smart heating" is just one more example of where Bitcoin in theory does not match Bitcoin in reality.
That's a fair point, but isn't your beef with externalities associated with electricity not electricity itself? Blaming bitcoin sound like whack-a-mole where you can blame video games, AI, whatever for wasting electricity. The real problem IMO is that electricity consumers create negative externalities, be it from making their home a bit too warm and comfy or from using a crypto-currency instead of a gold bar.
I think when people complain about emissions from Bitcoin, their beef is really with both energy emissions and Bitcoin. If our energy production did not pollute, then I wouldn't care how much people mine it, but as things are now, it seems wasteful.
It is often considered more wasteful than those other things you listed because the mining algorithm is designed to be wasteful; i.e., if people design faster mining chips, it doesn't make anything more efficient or increase economic growth, it just causes the hashing difficulty to increase among all miners. That is sheer stupidity.
Given that bitcoin is just one tiny piece of massive electric inefficiency in our world today, do you not see eliminating externalities as the goal at hand? I just don't see how you can possibly solve your worries without getting to the root cause. IMO electrical production emissions damaging 3rd parties is the problem and bitcoin outrage is the symptom. Eliminate bitcoin and something else maybe picks up the electrical slack, with no real assurance what it will be.
