There's nothing stopping you from learning everything on your own. BUT you miss out on the MBA network. When you're forced to spend 2 years with a cohort of 75-100 people, you develop a close-knit bond when you spend most of your time eating, drinking, studying (and sometimes sleeping) with these people. If I want a job at a company that one of my MBA classmates works at, an interview is literally one phone call away.