Earlier quoted context omitted.
My R730 averages at around 100-200W with two 12-core CPUs, 128GB RAM and 8 12-14TB drives. Servers are more efficient than people give them credit for. It's close to a gaming PC in electricity usage. Certainly not 60W (or what people can get with NUCs and RPi clusters) but for the power I get, it's very much worth it.
If we average that out to 150W, that'd be 1250-1300Kwh/yr. Current Bay Area electric prices means that'd cost in excess of $500/yr to run. I'd say that servers are not more efficient than people are giving them credit for...
Edit: But even at $500, that's pretty much the price of a low-spec VPS or VM per year. So for a fairly low initial price to buy the server, you're getting far more performance for the same price you'd pay someone else to use theirs.