Here's why:
* "Wait" is a verb. It indicates an action or state of being.
* "To" is part of the infinitive form of the verb. In this case, the infinitive is "to wait".
* Infinitives are made up of the base form of the verb + the particle "to".
So, while "to" might look like a preposition (like "to the store"), it's actually acting as a crucial part of the infinitive verb form in this context.