> Are you saying the number of transactions the market will demand of a system is independent of the trust of the system
No. I'm saying that if a 51% attack is practically impossible today, the increasing amount of energy consumed to secure the same amount of transactions is wasted. It's also a sign that the system is broken because the amount of energy consumed has no practical impact on security. Reasoning otherwise would suggest it is justified to consume infinite energy because that would be infinitely secure.
It appears you think a 51% attack is when an external agent attempts to out hash the network. This is only one type of 51% attack.
A 51% attack means there is a almost equal amount of hash rate being applied to two divergent, consensus equivalent chains. This can happen in above scenario or when existing miners attempt to reorg blocks (See ETC 51% attack) There is nothing stopping this behavior from occurring at any point in time. The only check on this behavior is the cost to rewrite history, decrease this cost, and you increase the profitability of such attacks.
No. I'm saying that if a 51% attack is practically impossible today, the increasing amount of energy consumed to secure the same amount of transactions is wasted. It's also a sign that the system is broken because the amount of energy consumed has no practical impact on security. Reasoning otherwise would suggest it is justified to consume infinite energy because that would be infinitely secure.