Answer:
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.
What can burn the eyes, sting the mouth, yet be consumed?
Three little letters, a paradox to some. The worse that it is, the better it becomes.
It is the electronic version of junk mail or a salty meat in a can.
What loses its head in the morning and gets it back at night?
Break me and I am better immediately set and harder to be broken again.