You can try to remember that 'to' followed by a verb form ending in -ing does not make an infinitive. The infinitive of a verb consists of 'to' followed by the 'base' version of the verb (the version found in a dictionary).
Thanks for responding. I meant to ask if there's a way of knowing when "to"is a preposition without knowing the verb that follows it.
With "I'm entitled to have," how am I supposed to tell it's have and not having?
Thinking on it, "I am used" + "to" as a preposition seems like the exception, while the "I am entitled" + "to" as an infinitive marker seems more common. I am interested to, I am excited to, etc...
I wondered what makes the two different from each other that informs the way "to" acts.
Hopefully that makes sense.