Why F- is more stable than CH3-

When I was reading Organic textbook, I saw a statement of 'F- is more stable than CH3- because the F has a greater electronegativity'. I agree with the explanation 'because of its high electronegativity, F can hold the electrons very well'. But I am just confused about: as the F has great electronegativity, it can react with other cations/electrophile very easily, making it reactive thus unstable. So I am just very confused about this contradiction.


