Well, I guess building your house is part of building the nation. If everyone did that, the nation would be built. On the other hand, building the nation protects the life of your future generation, just as the wall Jedaiah son of Harumaph built to protect the nation stood to protect his own house. He wasn’t alone (3:22, 23, 28-30). He must have been considered a smart man, I won’t disagree.