Important to note also, this blog article is aimed at students, who don't have significant domain experience in any field most likely.

Therefore, his advice is sound for this audience as giving up big ideas is necessary when they're so nebulous and you don't have anything you could apply it to. An entrepreneur, by definition, has a skill in 'making something people want' and getting them to give you money and can apply that skill to a field, regardless of if they have much experience in that field.