Return On Ignorance

Let's pretend for a minute that we can measure ROI for advertising.

And let's pretend we've measured the ROI for our brand this year and it turned out to be 10%. In other words, for every $1.00 of advertising cost, we got additional sales of $1.10 and, therefore, a return on our investment of 10%.

So the question is, if that is true, why not spend every dollar we have on advertising? I'd be