Someone has designed, hand manufactured and tested many versions of the product, put hundreds/thousands of hours' time into that then gone through the effort to get them manufactured in production quantities, made packaging, built a website/commerce channel and distributed that product to retailers. They have made it their business to provide solutions to problems that are hard, expensive or impossible for a bike shop or DIY mechanic to solve and build a reputation on doing so cost effectively.
The risk of negative return is fairly high. If their solution is needed in large volume, the manufacturers are likely going to make a product that eliminates the problem (e.g. a Road lever compatible with V Brakes.). When this happens, the R&D costs that has yet to be recovered is lost. Some products recover their costs many times over, but that makes up for the ones that lose money. To stay in business, they need to dance a tightrope while reading a crystal ball - charge enough to remain profitable but charge too much and you damage brand reputation and reduce sales volumes and profitability.
It’s not about $1 of billet aluminium and a roller bearing, it’s about everything else.
Why have prices gone up - They gave a story about interest and inflation and tariffs, which all contribute, but ultimately, because to remain in business they felt they needed to increase price.
