Why are there many more Main-Sequence stars than Red Giants?

Main sequence stars are where stars spend the majority of their active lives.

When a star with less than 8 solar masses runs out of hydrogen to power its core, it contracts due to gravity. At sufficiently high temperatures and pressures, helium fusion begins, which causes the star's outer layers to expand and cool, transforming the star into a red giant.

A star's life as a red giant lasts only a few thousand to a billion years before it collapses into a white dwarf.

Because the red giant phase of a star's life is relatively brief, there are more main sequence stars than red giants.

The bulk of stars will eventually form as white dwarfs, neutron stars, black holes, and ultimately black dwarfs at the end of the fusion stages.

Red giants are a later stage in a star's evolution that occurs after the exhaustion of hydrogen fuel in the core. This phase is relatively short compared to the main-sequence phase, meaning that there are fewer red giants at any given time. Main-sequence stars outnumber red giants because they spend the majority of their lifespan in that stage.