What I have learned when using ads is to TOTALLY IGNORE Amazon's suggestions because those suggestions ONLY benefit Amazon. Their suggestions HAVE NEVER led to my increasing profit. Take small steps, use lower budgets and minimal keyword prices to see what words are helpful or wasteful. Ignore their keyword price suggestions by half or more. Adjust weekly as you see the ROAS for that campaign. Bear in mind that the ROAS is only a reference since it does not take into mind your actual costs to create, ship, and manage the product. I always try to keep my ROAS over 5, or I am just paying Amazon to sell my products at cost.

However, I will allow a lower ROAS when launching a new product since it is a necessary step to receive product exposure and eventually get the reviews you need.

I understand your frustration about the $12,000. I did something similar on Google ads many years back, and it was a hard lesson to learn that any company that provides you with the capacity to place ads DOESN'T CARE if you make a dollar. They are only there to absorb whatever you are willing to bleed.

As others have already noted, Amazon does not hold your hand and seems to create unnecessary hurdles for what should be simple things. However, the overall bottom line is that Amazon's revenue capacity far outweighs what you can often experience elsewhere. There is no magic wand with placing a ton of ads. Work on getting reviews and improving product quality, images, and text; and then the product will eventually sell itself.