Security of PoW depends on continuously using more resources than an adversary can gather. It has to always cancel out any advancements in efficiency, by design

Security of PoW depends on continuously using more resources than an adversary can gather. It has to always cancel out any advancements in efficiency, by design. It's unfixable in this aspect. This is unlike any other activity where resource usage is roughly proportional to the value delivered, rather than maximized on purpose. Even if we had a Dyson Sphere, we'd have to waste more than a half of it on mining.