What causes high cost?

Targeting USA only and a certain age group, is it normal to receive 17 impressions per $1.2?

Chatgpt answered my question.

“Yes, your targeting choices can impact the competitiveness of the auction for Facebook ads. When you define your target audience, you're specifying the characteristics, demographics, interests, and behaviors of the people you want to reach. If your target audience is highly sought after by other advertisers, it can lead to a more competitive auction environment. In a competitive auction, the cost per impression or click can increase as multiple advertisers vie for limited ad inventory.

Factors that can contribute to the competitiveness of the auction include the size of your target audience, the specificity of your targeting criteria, and the number of advertisers competing for similar audience segments. To optimize your results and manage costs, it's essential to continually monitor and refine your targeting, adjust your bidding strategy, and experiment with different approaches to find the right balance between reach, relevance, and cost-effectiveness for your ads.”

Which gives me an idea.. what if one experiments to find the lowest competitive targeting options and tailors affiliate offers or custom services/products to that audience within tier 1 countries? That’s a winner simply from the familiarity from high frequencies in itself, you can input enough budget to be “relevant” in their eyes with lower cpm costs. I remember receiving hundreds of sign ups with an extremely high frequency stat back in the day.
Testing a narrowed audience now, using mobile so learning things are a little different coming back to it. Will update if I make an astonishing discovery which I usually do.

Only age group is not the factor. There are tons of other factors that can affect it like keywords you are targeting, competition, CPC etc.

What is the goal of the campaign?

There are factors to be considered, such as your target audience, niche, competition, ad targeting, and the effectiveness of your marketing strategy.