Who benefits under absolute monarchy?

Well it depends on the monarch. If you have a good one everybody benefits, if you have a bad one nobody except the monarch does. That is the problem with the monarchy system. Having a single individual in charge of the government has a few advantages. It is more focused and stable in many respects. The problem comes in making sure you have a good monarch on the throne. Democracy is much less focused and variable. Decision by committee is much more likely to change and be slower to do so in a crisis where rapid decisions are needed. The advantage of a democracy is that one bad ruler is much less disastrous than an absolute ruler would be and frequently has a much shorter term in office.  more