Maybe my assumption of profit margin is not correct?
It's not so simple. There's R&D, market positioning, technical expertise, etc. True one must generate enough profit/revenue to cover costs for a business to survive, more to make the effort worthwhile, but there is much more to consider.
Sometimes reducing the profit margin (sales) to get deeper market penetration, to stimulate brand interest, and/or to reduce inventory (prevent from being stuck with outdated inventory, sell inventory to free up cash maybe to fund other projects).
One cannot easily play with the profit margin. To increase the profit margin, one would have to reduce costs and/or increase price. Reducing costs is very limited as you'll soon get to point where quality will decline. Raising prices is limited by the competition, beyond a point you'll loose sales to the competition. Audiophiles are adept at recognizing price/performance, we have to at these prices