Be smart, no matter how hungry you are.

wasn't he on the verge of starvation? cause if he was then your birthright doesn't seem as important, cause what're you gonna do with it if you're dead?

His birthright gave him inheritance from his father, which was extreme wealth and such, and he could have just killed an animal on his property

my point still stands, also there likely weren't any around his home because he did so much hunting that he was on the verge of starvation