Isn't that "waste" heat still warming the planet? Isn't turning a cold planet into a warm planet a good thing and therefore the "waste" heat is still "used" for something useful?
Toy ODE model:
dx/dt = -k x + a + b.
Here, x is temperature, a is solar heat input, and b is heat input from human sources. I'm dropping some coefficients that would make the units strictly work. We have a >>> b. The coefficient k says how easily the Earth radiates heat. Adding greenhouse gasses makes k closer to zero.
At equilibrium, dx/dt = 0. Solving,
x = (a + b) / k ~= a / k
Again, b is tiny relative to a. So almost the only thing that matters is k.
We actually spend quite a bit of energy doing the work of moving heat from colder to hotter areas because humans don't like to be too hot.