In my college days I had dreams of passive income, because I wanted to self-fund a career as a writer/director of micro-budget indie movies.
A friend told me about a friend who claimed to be making loads with affiliate marketing, so I started to immerse myself in performance marketing, the lifestyle was just too attractive.
I started with a $100 FB ads coupon and by the time that was spent I luckily stumbled on a profitable campaign.
I quickly realized that the globalized economy is extremely competitive, and internet businesses with low barriers to entry are radically hyper competitive.
There was no way to be completely passive and successful.
So I obsessively scaled my profitable campaigns and researched and experimented with new ones. I went to conferences, and sought to strike better deals with affiliate networks and even sought direct deals with the companies whose products I was selling.
I spent a lot of time building relationships with the ad reps of the companies I was buying ad space from.
I did a lot of industrial intelligence to find what was working and what wasn't.
My girlfriend at the time was finishing her last year of college and I did all of this while she was at class. When she finished school we embarked on a cross country trip, went to a lot of music festivals and moved to Boulder, CO.
It was a pretty sweet lifestyle for a while.
The money was still coming in from my old campaigns, but the distraction of being on a permanent working vacation took a toll on my efforts.
Then the industry kind of imploded. The field got incredibly more competitive and a lot of affiliates began engaging in outright fraud to increase conversions.
Because of the unethical behavior, the companies I was buying traffic from started making it harder for affiliates to operate, they wanted national brands as advertisers and I don't blame them.
The industry was scummy, not so much because the conferences I went to had their opening night festivities at strip clubs. Or that even at the relatively more respectable events naked women wearing only paint would serve drinks.
It was just corrupted by the huge amounts of easy money made possible by the implosion of the global economy and the resulting plummeting of ad rates combined with the deceptive marketing practices employed by the affiliates.
When more and more people heard about the easy money available, only the sociopaths or otherwise ethically impaired could profit.
My dreams of easy passive income were dashed and I threw myself into software development. Now I create real value, instead of exploiting narrow arbitrage opportunities.
Making amazing software products is so much more valuable, rewarding and sane than film making anyhow.
To answer your question, is it possible? Yes it is, but it is very dependent on market conditions and they are forever trending to be less favorable.
There are still incredible opportunities in lead gen (better connotations than affiliate marketing) but these days you have to build a platform that delivers real value instead of just buying cheap traffic and selling it for more.