(musician/celebrity) S/he is at the height of his popularity
(in general) S/he is unbeatable
(in general) S/he is unstoppable
とにかく一番トップにいる、というニュアンスで
(musician/celebrity) S/he is at the height of her/his popularity
一般の人なら
(in general) S/he is unbeatable
unstoppable→すごい、ずっと前に進む人
過去ならisがwasになる。