I think it's because the most profitable methods result in the least amount of conversation. That or everyone doing media buying is actually not making money and faking-it-until-make-it.
How much do you need to get started with this?
It definitely works. But it requires a budget. A minimum of 1000$ is needed, but i would suggest 2000$ or even 3000$ - The reason for that is because its very expensive to test offers. Lets say you are running an Adult Media Buying Campaign on NTV A and NTV B Placements on popular sites (such as Pornhub, Youporn, etc.) - In Media Buying a lot of stuff comes together to make a perfect funnel, and if you just miss one thing in your funnel, then the conversion rate can result in a negative ROI.
So going back to the Adult Media Buying Campaign, first of all, if you are targetting T1 Countries (UK for example) you are going to have a hard time getting good traffic. That's because you are competing against people with a high budget and a well optimized blacklist/whitelist for their traffic. If you are running Adult Ads you need to be comfortable to spend at least 50$ per day just on testing the offers. The other problem is banner blindness. Banners tend to do well for 2 to 3 days until it starts to perform bad, so you always need to be ready to replace banners quick. You also need to have a good hosting, preferably a CDN to get your site loaded up as fast as possible (especially if you are doing POP). Then you also need to have a great converting offer, and that can be one of the hardest things to find. There are a ton of offers out there, but a lot of them either suck, don't convert well or just simply get pulled once you send traffic (because the advertiser does not like the leads), so you need to take massive action on finding the right offers. And of course, you need a tracker such as Voluum or Binom, which tracks all your data so you can do optimizations.
The learning curve in media buying is steep, as it requires a budget, an open mind and lots of failing along the way to the first sucessful campaign. Once you have found a winning campaign, you need to bid accordingly so you don't get greedy and bid higher, to the point where your ROI turns into red.
This was a recent campaign i did in a T3 Country with an exceptional payout. I left the campaign running for 30 minutes and got about 162 conversions, just alone from those 30 minutes. Now imagine what would've happened if i let the campaign run through the entire day. Unfortunately for me, the advertiser pulled the offer and i couldn't scale it further. But that's part of media buying.