The first 3 Falcon 1's failed. Elon put up his last dollars to make the 4th one happen, (at the same time as he put a bunch of money into Tesla to make sure it survived long enough to get Roadsters out). 4th launch of Falcon 1 was a success, and gained SpaceX commercial customers.
Falcon 9 is a derived but unique design. It isn't fair to count failures of an early design with those of a mature design.
CRS-1 in October 2012 was the partial failure. It launched to ISS with a secondary payload for another customer which was to be sent to a higher trajectory. During ascent, one of the 9 engines lost fuel pressure and was shut down. This necessitated a longer burn on the remaining 8 engines, and left the rocket with less fuel than it otherwise would have had. NASA required greater-than-99% probability that the secondary payload would reach its orbit clear of the ISS, and nixed the secondary mission. SpaceX believes it could have successfully achieved it. NASA made the call to abort the secondary mission, as their mission took priority.
CRS-7 in June 2015 was the only total vehicle failure of Falcon 9. A strut inside the LOX tank which holds a helium tank inside gave way, and caused a failure of the LOX tank when it collided with the LOX tank pressure vessel, resulting in a RUD during ascent.
Reports coming in now seem to suggest it was a pad anomaly, and not a vehicle anomaly that resulted in today's problem. Rockets by their very nature have a lot of boom stored. Bad things happening in the vicinity will cascade.
