The requirements of a successful start-up

After watching many start-up companies succeed or fail, I've come to the realization that the requirements of a successful start-up company these days are: 1) solid management having a great network of relationships and contacts, 2) luck/timing, and 3) a darn good product.  Expanding these a bit:  1) People solve problems.  People buy products/services.  People tell others about your product/service.  The broader your reach into your industry, and your market, the better you will be able to solve your problems and sell your products.  2)  You have to admit, timing is critical.  Hitting that market window is critical.  And in this is some degree of luck, which none of us can control.  And finally, 3) you have to have a product that has sizzle...that compels users/customers.