Right, the energy use goes up with the value and (separately) down over time. They’re separate variables, but it’s fair to point out that they're not independent variables (the price is more likely to vary over a longer time horizon), which is I think the point you’re making?
You are not taking into account the diminishing block reward. More and more miners are chasing a dwindling supply of coin and will eventually only earn transaction fees and no block reward. This will put a natural dampener on more miners coming in (all other things being equal) and it will plateau.