M K,
I was a management consultant in Sydney for a few years at a boutique firm.
For many people (I would argue most), working in management consulting at a reputable firm during the early years of their career is a stepping stone job. It can provide the skills, connections, and branding needed to open new doors to new opportunities.
The work itself is high paced and the hours can be long, which suits some people, especially the kind of high achievers who are attracted to work in management consulting. Of the dozen or so friends who started with me in consulting, all have subsequently moved on to other things.