Capital costs matter, especially for anything that's only run part-time. Buying servers that sit idle for half the year (during summer) would effectively mean they take twice as long to pay for themselves compared to servers that run all year. So that's at least twice as expensive.
Maybe the numbers would still work, but you have to actually do the math.
Just send the servers to the southern hemisphere for half the year (when it's summer here and winter there) and then back for the other half. Problem solved!
Maybe the numbers would still work, but you have to actually do the math.