Except Bitcoin is inefficient by design (it’s what proof of work is) and the dosage is the market cap and transaction load. So what you’re really saying is bitcoin at the scale it was meant to operate at is poison.

No, the dosage is the hash rate (if more hash rate joins, the difficulty is automatically adjusted to keep it at 1 blocks / 10 min). The transaction output is constant, and market cap is irrelevant to the energy inefficiency discussion.