Why do brown dwarfs never evolve?

These objects, known as brown dwarfs, have many of the elements of their more famous siblings but lack the mass needed to jumpstart nuclear fusion in their core. ... Because brown dwarfs never burn fusion at their core, scientists sometimes refer to them as "failed stars."

Sugar + oxygen > carbon  dioxide + water + energy  c6h1206 + 6o2 > 6co2 +6h2o + energy  and the numbers after the element symbols are small.