Couldn't "Plus I have my interests pretty fixed." be the answer to that question?
On the other hand, watching my own kids, its star wars today, gone tomorrow. Minecraft today, gone tomorrow. Lego today, gone tomorrow. Even if you could track my son and accurately predict his current interests, knowing that he WAS really into star wars a year ago is pretty much financially useless given that he seems to be into lego branded cartoons right now, although next year both will be forgotten in favor of something else.
One poster has a middle-aged interest in hard sci-fi; for $x advertising allocation per individual it's going to be difficult to shift his interests. The same $x applied to teenagers year after year 'flips' them from one revenue-generating interest to another. And sets them up, the advertisers hope, for a non-niche middle-aged interest.
The first one is simple: Facebook and other social apps are about network effects and habits: checking daily to see what your friend are up to, while sharing the same. I'm not sure what the stat is in the past year, but for every year since it started the most stunning stat to me was that 50% of their users checked every day. When the habit starts to erode the network effects can cause acceleration, raising questions about Facebook's future.
The other reason is that teens are a very hard demographic to reach. Twenty years ago, companies could air commercials on MTV, put ads on FM radio, and create full page ads in magazines to reach teens. Today, teens are doing a lot less of this. As a result, companies that can reach these younger audiences can charge a hefty premium due to scarcity. You're a highly desirable demographic as well -- 25-44 with disposable income. But they already have ways to reach people like us.
Lets play a fun game. Only us wanna be near senior citizens get to play. Its claimed that its financially valuable to monetize teen "tech" fads, now that we're old and wealthy lets see how companies are cashing in on our teen years, to get an idea of how incredibly valuable it will be to cash in on todays teen fads.
1) The music market dominance of heavy metal and grunge, and cassette tape as its delivery medium.
2) Beanie babies as an investment portfolio, also baseball cards. I'm a hair too young for the MtG card fad.
3) AOL chat rooms lead the market, as does AOL in general.
I will admit defeat in womens fashion which follows a generational pattern, where my mom wore bell bottom pants, therefore all the girls were wearing bell bottom pants again, 20 years after she did. Similar patterns in the popularity of tights/yoga pants, and the cyclical nature of miniskirt length. But these are not tech related issues and they appear impossible to profit off of, unless you're in the biz and you simply ship this year whatever was cool 20 years ago.
I've been hearing this claim that teens are molded into inflexible consumers all my life without any actual citations, so I feel safe calling it bogus in the future if its always proven bogus in the past.