The highest paid workers in Silicon Valley are product managers (2016)
I can only think of product managers deserving such high salaries for customer facing products. They can act as translators between end users and engineers. Having worked on purely backend ML code, I find PMs to be mostly clueless about how the product is built. Even after spending years on a product they may not understand simple things like names of different components and what they do. Even during quarterly planning meetings, which is the PMs time to shine, half of the ideas on the table can be dismissed for being impractical and the other half require some data collection to dismiss. At least for backend work I think a Tech Lead can do all the tasks of a PM.