I note that you failed to respond to my high-level point that makes all your technical minutiae irrelevant.
> My point was that people are OK to spend energy on things that are seemingly useless (shiny colorful lights, or SHA256 computation.)
Not the same thing at all. People enjoy looking at colourful lights, and so choose to pay to display them.
> Every kWh spent on Bitcoin mining not only enables transactions, but also: creates jobs, creates wealth, reduces trade friction, improves economic output, and on and on.
In a hypothetical large-scale Bitcoin economy, how many transactions would happen that wouldn't have happened without bitcoin, what proportion of those would be transactions that were positive rather than negative for society, and what would be the energy cost per such transaction?
> And yet reversibility hampers trade. Some business is never done with reversible CC transactions precisely because merchants can't accept the risk. Bitcoin enables them to pursue ventures that would otherwise not be doable.
We have techniques for doing irreversible transactions in the existing financial system. They're used for a tiny proportion of transactions, and an even tinier proportion of legitimate transactions, because the overwhelming majority of the time reversibility is what you want.