Why though?

And when does this start being for everyone? We have had agricultural machines for ages, but I still have to pay an ever increasing part of my salary (and hence time here on earth) not to starve.

Because of asymmetry. Some people are more inclined toward certain things than others. People who are excellent at math are much more likely to be able to advance AI for instance. The goal of physical systems being to remain at rest/(humans included ;) the gradient of resources lean toward these people so that they can improve the technology allowing everyone to be able to conserve their energy (be lazy in a sense).