[cecilpl2]

> You are not paying the full electricity cost for mining Bitcoin in transaction fees, the generation of new coins is offsetting some of that cost.

This is the big factor.

As the block reward decreases, transaction costs will need to increase dramatically.

[SilasX]

Or the number of miners contracts in response to the reduced rewards.

[danShumway]

If the network was amiable to increasing the number of miner contracts per block, wouldn't they have done it already?

Transaction speed and cost is already a regular criticism of the Bitcoin network. It's so much of a criticism that the Bitcoin community made the Lightning Network and started pulling transactions off-chain and pooling them to address that concern.

But they didn't collectively decide to increase the number of allowed miner contracts. They literally built a second network rather than change the max block size.

And in fact it was not only not accepted, it was a big source of controversy to even try to increase the block size. That was the whole deal with Bitcoin Cash, people were outright hostile to this idea.

[SilasX]

>If the network was amiable to increasing the number of miner contracts per block, wouldn't they have done it already?

“Contracts” is a verb in that sentence, not a noun, and yes, miners do leave the market as it loses profitability, and no, the network does not have a requirement that there be a minimum number of miners, and there are reasons why they haven't left now but might not leave in the future.

You're not using the "why haven't they done it already" heuristic correctly.

[danShumway]

Oh, I see what you mean -- you don't mean contracts as in the number of miner's transactions/rewards per block, you mean contracts as in "the miner pool decreases in size." My bad, that was a mistake on my part.

Agreed, that's definitely a possibility, and that would improve energy usage. However, it would also make the network more vulnerable to 51% attacks, and if Bitcoin were to have enough value to actually replace a financial market, it would need a lot of miners to secure that value or it likely lose that value.

But... quibbles aside, you are completely correct that if mining stops being profitable then fewer people will mine, and that is also the correct answer for how to deal with Bitcoin's energy usage. Bitcoin miners will use as much much energy as it is profitable for them to use, and the only way to make that energy usage go down other than banning crypto would be to decrease the profitability of mining (ie, by keeping transaction fees and payouts low and by reducing other mining rewards) -- and that could be accomplished through either reducing the rewards, moving to another system like PoS that removes the miners entirely, or by Bitcoin's price crashing.