From my experience from years ago, once the ad revenue reached certain threshold, it was limited or reduced afterwards to never reach that threshold again. For

From my experience from years ago, once the ad revenue reached certain threshold, it was limited or reduced afterwards to never reach that threshold again. For instance, website of someone I know was growing and at one point got £1500 from ads in a month. The next month it has dropped to £500 and never gone over £600, no matter how big of the traffic was hitting the site. That was revenue for about 500k monthly unique users (EU, UK, US, no dodgy traffic). It's like an artificial cap was placed on that account. Finding companies to advertise directly was difficult, because they already used established platforms and were reluctant to deal directly. And so small business eventually died.