Symantec is it's own worst enemy
Symantec really doesn't do itself any favours with its bloated suite of consumer and commercial products. Sure, they work, but at the cost of performance and over-complexity.
Arguably Goliath was toppled as he was so large. The ever-bloated and expensive Norton Internet Security suite is a good example; it'll bring a system to its knees with the load it puts on the client. 7 years ago it was fresh and good, now it's grown into an expensive lardy monstrosity.
The market is ready for alternative products. Particularly good-value products.