He had a rough childhood, sufferinf at the hands of his alcoholic father, who was a policeman. Managed to get away and worked hard to make a success of his life, very much aided by his meeting with Jim Steinman. Even then, he certainly had lots of ups and downs in middle age but he triumphed and was a smashing artist and showman.
You don't get musicals written about you unless you have achieved something!
RIP Marvin.