Why are alkali metals not found in nature?

(N/A) Alkali metals include lithium $(Li)$,sodium $(Na)$,potassium $(K)$,rubidium $(Rb)$,cesium $(Cs)$,and francium $(Fr)$.
These metals have only $1$ electron in their valence shell,which they lose easily due to their low ionization energies.
Because of this high reactivity,they readily react with other elements like oxygen,water,and halogens,and thus are not found in nature in their free elemental state.