What causes massive stars to exhaust their large initial hydrogen fuel reserves quickly?

Their burn rate is excessive due to intense internal pressure

Although the most massive stars possess the largest initial reservoirs of hydrogen fuel compared to smaller stars like the Sun, their existence is brief because of the rate at which they consume this fuel. To maintain the necessary hydrostatic equilibrium against overwhelming gravitational forces, the core must operate under immense pressure and extreme temperatures. This condition compels the hydrogen fusion reactions to proceed at an excessively high rate—a 'roar' compared to the slower 'sip' of low-mass stars. This ferocious burn rate ensures that even though they start with more fuel, they exhaust that supply rapidly, leading to a very short cosmic lifespan.