Why don't tropical cyclones hit Hawaii?
There are at least two effects are at play here: 


Hawaii is a tiny speck of land in a big ocean; the odds of hitting any given spot in the Pacific with a storm in any given season is incredibly low.
The waters around Hawaii are deep and generally relatively cold, they suck energy out of storm systems that pass over them causing cyclones to downgrade into tropical depressions before they hit the islands, so there are plenty of storms but few are still cyclone grade when they arrive.