It is unusual to be able to make a living working in that field.
People don't usually make enough money to live on working in that field.
“People don't usually make enough money to live on working in that field. So I think you need a lot of resolve. (その分野で普通は食べていくほどのお金になりませんから、相当な覚悟が必要だとお思います。)「並大抵じゃない」は “unusual” と言います。「食べていく」は “make a living” と言います。