system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA] Why are fire benders the only ones who can spontaneously generate their element?

In the Avatar universe, fire benders are able to spontaneously generate their element.  They can actually conjure fire from nowhere.  Other benders however, are limited to manipulating existing sources of their element.  We see this reinforced several times.  Katara always carries a waterskin with her so she has water to bend at all times.  Earth benders are imprisoned at sea away from sources of earth to bend.  So why is fire different?
gpt
Firebenders are different because they're not necessarily bending what's around them, but what's within them. Their fire is a manifestation of their chi, driven by either their passion or their anger. In many ways firebending is closer to energy bending than it is to Earth or Water bending.