$ 1 9 . 3 ▁billion . ▁ ▁In ▁ 2 0 1 4 , ▁he ▁entered ▁the ▁For bes ▁list ▁of ▁the ▁ 4 0 0 ▁rich est ▁Americans ▁at ▁position ▁ 6 2 , ▁with ▁an ▁estimated ▁worth ▁of ▁more ▁than ▁$ 7 . 5 ▁billion . ▁He ▁was ▁the ▁highest - rank ed ▁new com er ▁to ▁the ▁list ▁that ▁year . ▁ ▁Early ▁life ▁and ▁career ▁K ou m ▁was ▁born ▁in ▁K iev , ▁Ukraine , ▁then ▁in ▁the ▁Soviet ▁Union . ▁He ▁is ▁of ▁Jewish ▁origin . ▁He ▁grew ▁up ▁in ▁Fast iv , ▁outside ▁K iev , ▁and ▁moved ▁with ▁his ▁mother ▁and ▁grand m other ▁to ▁Mountain ▁View , ▁California ▁in ▁ 1 9 9 2 , ▁where ▁a ▁social ▁support ▁program ▁helped ▁the ▁family ▁to ▁get ▁a ▁small ▁two - bed room ▁a partment , ▁at ▁the ▁age ▁of ▁ 1 6 . ▁His ▁father ▁had ▁intended ▁to ▁join ▁the ▁family ▁later , ▁but ▁he ▁never ▁left ▁Ukraine , ▁and ▁died ▁in ▁ 1 9 9 7 . ▁K ou m ▁and ▁his ▁mother ▁remained ▁in ▁touch ▁with ▁his ▁father ▁until ▁his ▁death . ▁At ▁first ▁K ou m ' s ▁mother ▁worked ▁as ▁a ▁b ab ys itter , ▁while ▁he ▁himself ▁worked ▁as ▁a ▁cleaner ▁at ▁a ▁gro c ery ▁store . ▁His ▁mother ▁died ▁in ▁ 2 0 0 0 ▁after ▁a ▁long ▁battle ▁with ▁cancer . ▁ ▁By ▁the ▁age ▁of ▁ 1 8 ▁K ou m ▁became ▁interested ▁in