It is psychological security too. Most ads are manipulative inducements to expend money that could otherwise be more cerebrally spent elsewhere (or saved even). Our goal as individuals is expense reduction, which is an economic strategy that is diametrically opposed by any individual or business reliant on you spending money. Ads are the vector where psychological games can be played to erode our default economic strategy. Ads are an evil most don't recognize, and need more controls than firearms even!