Why don't all red giants turn into white dwarfs?

Fusion creates extra radiation pressure, and this will cause the Sun to expand. The outer layers of hydrogen will decrease in temperature, which will make them redder, and the Sun will then be a red giant. All main sequence stars that are about 1/5 to 10 times the mass of the Sun will become red giants. read more

12.2 White dwarfs Over 97% of stars in the Galaxy will become white dwarfs. White dwarfs are stars that have ceased nuclear fusion, but still emit light from stored thermal energy. read more

However, these outer layers are not vary stable and are quickly blown away, leaving behind an intact core, surrounded by a cloud of gas known as a planetary nebula, marking a phase of transition from a red giant to a white dwarf. read more

The Sun, and any red dwarfs above about 0.25 solar masses, will expand into what's called a red giant, a late stage of stellar evolution. At this stage, the star starts to fuse different elements, and eventually throws off its layers as a planetary nebula, leaving behind a white dwarf made of carbon and oxygen. read more