Why do you think the Earth has a insanely hot core?

Pressure. Put anything under enough weight and it heats up. Science!

Insanely hot, or just hot body, ugly face?

Love energy

Yeah, we do know.

Ever heard of hell??

The core is hot because of of the decay of radioactive elements. All that energy had nowhere to go; it melted the inside of the Earth to the point it first became molten and then the fluid rock and metal became even hotter, as hot as the surface of the Sun.

Eventually hot plumes of magma reached the surface and caused to plate tectonics. At that time the interior stopped getting more and more heated because energy was now released at the spreading centers

Tell me more about the hot core. It's kinda sexy

Because they never lied about anything else

If I had to guess, it's because we have a rather large moon in orbit around us and gravitational forces pulling at the mantle and core material heats it up quite a bit from friction. Some of the heat is just residual from the planet's formation. Also, the outer core is liquid metal that is spinning, which generates the magnetic field and also quite an electrical current which heats up the interior of the Earth quite a bit too.