Some of us live off-grid. Some of us live on-grid but the grid is unstable (or we think it may become unstable in the future). Some of us do not have the same time/effort versus money tradeoffs that you do. Some of us want to reduce our emissions more than others. Some of us just really enjoy optimizing.
It registers to me as the same sort of impulse that drives optimizing a bit of rarely-used code. It's more of a principle-based interest than a practical one. In other words, it's very human.