We have shown that higher dimensional Reissner-Nordstr\"om-de Sitter black
holes are gravitationally unstable for large values of the electric charge and
cosmological constant in D≥7 space-time dimensions. We have found the
shape of the slightly perturbed black hole at the threshold point of
instability. Why only D=4,5 and 6 dimensional worlds are favorable as to the
black stability remains unknown.Comment: Essential new material is added, references added, 5 figures, 1
table, RevTe