"Why do they tell us in their books that aliens are real, and that I am a special indigo starseed moonbeam?"
Simply because they can. As an empathic person yourself, who is seeking answers and wanting to improve yourself and the world around you, you are a prime target for psychopaths who will treat you like little children.
They believe they are superior to you, and therefore just like we as adults will play fantasy games with children, by telling them Santa is real and play along with make believe games, so will the psychopath with you.
They will play with your mind, they find fun and power in feeling superior, so superior that they can afford to condescend to what they feel is your ridiculous level and play along with your little fantasies for a while. They see you are harmless, but a source of narcissistic supply, power and of course cash, so why would they not go along with your make-believe?
If they meet someone who thinks she's beautiful or smart or talented? Or think they are special (indigo, starseed, alien)?.. Then they don't see that there is anything wrong with lying. Remember you are a silly child, and they are superior, they like it that way.
Alone, away from their book signings and tours, in private, they will be drinking a beer and having a good old laugh at those silly fools who believe all the crap they write about.
People get angry at me for debunking this stuff, when really they should be angry at those who are actively lying to them, by pandering to their ego. But it is always more enjoyable to have your ego massaged than face reality isn't it? Well no, the truth is beautiful, try finding that inside yourself, and you will see.