You are detailing the cost to defend the whole blockchain and every transaction that has occurred. Classifying it as just the cost of a single transaction is misguided.

Layer 2 bitcoin solutions like lightning with infinite theoretical TPS (transactions per second) make this kind of math seem even more idiotic.

When lightning was implemented, you could no longer definitely say each Layer 1 Bitcoin TX is 1 transaction. In reality, any single bitcoin tx could actually be a batch of 10,000+ transactions settling on Layer 1.