Exactly--the average private citizen cannot afford and really has no vested interest in an F-22 or an interstate per se, but the Constitution provides for such in the preamble and in Article I, Section 8 because the interests of the nation as a whole depend upon it (i.e., national defense and general welfare vis-a-vis promotion of interstate commerce).
That being said, when government takes over a perfectly (or even imperfectly) functional sector of the economy such as banking, automotive, or healthcare, then it has exceeded its mandate and is turning socialist in nature. Just sayin.
Oh, and the adbot at the top of the thread? On foodstamps? Get a free cell phone? Priceless.