Obviously they obtain benefit form employment.

If it were multiple competing companies, the same output would probably require MORE employees. One of the ways it is so profitable is to implement economies of scale not possible in a less monolithic industry.

You are failing to see that extractive business models such as monopolies do not add value, they extract value and concentrate it in the hands of the execs/owners. This removes capital from the socio-economic system/society and reduces the capabilities of the whole system to grow (the occasional purchase of a yacht does not rebalance things).