why

I guess he needed a paycheck you dolt.

He was forced into monster roles by typecasting and the fact that he was the son of Lon Chaney. Chaney Jr. began his career as Creighton Chaney (his actual name), but film studios wanted to capitalize on his late father and basically starved him into changing his name to Lon Chaney, Jr.

He struggled for a decade in small roles until his breakthrough as Lennie in Of Mice and Men. Unfortunately, this typecast him as a huge, dumb brute and that was all he was offered until The Wolfman. The rest is, as they say, history.

Chaney was a limited actor and never got away from the shadow of his father. He was great in Of Mice and Men and did solid work in minor roles like the former sheriff in High Noon. Contrast him with Karloff, who was also in a lot of z-level movies and you will see the difference. Karloff somehow rose above the dreck and made the characters interesting. Chaney usually sank under the mediocrity.

Shunted aside from the major studios after 1950, he became an alcoholic and spent the rest of his career in low grade features. Even Roger Corman passed him up while he was employing Karloff, Lorre and Rathbone in a series of horror/comedies. Corman used Chaney in The Haunted Palace, and that was that.

One of Chaney's last memorable performances was in the cult favorite Spider Baby, where he managed to infuse his character with warmth and melancholy. He also made a number of forgettable horror films in Mexico just prior to he death.

Yet his best performance was in Dracula vs Frankenstein and he did not play one of the title creatures