In our case, it is a bad thing because it's not a sustainable cycle at our current population and way of living. If we don't come up with an alternative energy source that is not also dependent upon fossil fuels to build and maintain, civilization ends.

It's not looking good.

Plants get their energy from the sun via photosynthesis. They "eat" nutrients from the soil symbiotically alongside fungus. In their case, they "eat" raw materials for cellular building structure but their energy source to power the build is the sun.