You crucially missed the "halving" out of that model.
The block reward halving every 4 years means that in 3 halvings (8-12 years), miners will spend roughly the same on electricity at $1M/BTC as they do now at $125k/BTC.
Further, at historical rates of dollar devaluation, in a decade $1M will only be worth ~$500k today, and so really only roughly two halvings are required to even the electricity use between $125k/BTC and $1M/BTC
The block reward halving every 4 years means that in 3 halvings (8-12 years), miners will spend roughly the same on electricity at $1M/BTC as they do now at $125k/BTC.
Further, at historical rates of dollar devaluation, in a decade $1M will only be worth ~$500k today, and so really only roughly two halvings are required to even the electricity use between $125k/BTC and $1M/BTC