Remember the mass-luminosity relationship:
Question: what causes this relationship?
This can be roughly fit by a power law: L ~ M4.
The fuel in the gas tank is hydrogen. The rate at which the fuel is burned gives the luminosity. So the lifetime on the main sequence is proportional toTms ~ M/L ~ M/M4 ~ M-3
So massive stars live for a much shorter time!
Mass (Msun) Main Sequence Lifetime 1 10 billion years 1.5 1.5 billion years 3 250 million years 5 70 million years 9 20 million years 15 10 million years