Complete and utter tosh, have you been on the wacky backy again?
Nothing is essential except food water and air but maybe you should get rid of your bike, car, tools, clothes and house, go and live in a cave where you belong.
You will have disposed of your power and hand tools and reverted to bits of flint so won't even need your oilstones. Best of all no computer so we wouldn't have to read your copious amounts of carp.
Adjustable or variable speed on a lathe is very useful indeed and is adjusted according to the size and properties of the wood or other materials you're turning, sanding or applying a finish to. Higher speeds are used for small spindle work say a pen blank than the lower speed needed for a 12" bowl blank and is adjusted as you progress from rough to a cylinder. You really need to go and have a few lessons.