Here's why:
* Infinitives are the base form of a verb, usually preceded by "to". They can function as nouns, adjectives, or adverbs.
* In this case, "to help" is the base form of the verb, and it can be used as a noun (e.g., "To help others is important"), an adjective (e.g., "I have a desire to help"), or an adverb (e.g., "I came here to help").