How insurance should work: Disasters are unpredictable, are bound to happen and can be very expensive to resolve. So instead of each individual risking bankruptcy for participating in a system, everybody pools together money at a much lower individual cost. That money goes toward a statistical guarantee that the cost of any disaster will be covered.
How insurance actually works (under capitalism): For-profit companies use every tool at their disposal, regardless of ethics or legality, in order to take as much of your money as they can possibly get away with while simultaneously paying out as little as they can possibly get away with, and then pocket the difference.