Personally I read "having" enlightenment as a type of identity view, attributing enlightenment to a "self" as if the self is something -- instead I think it might be "less wrong" for me to consider whether enlightened behavior is or isn't (currently) present.
I think that's the bulk of the way in which it's taught in the suttas -- i.e. "good/skillful behavior is good and leads to nirvana" and so on, the talk is about the behavior not the person (though there is also talk of karma)
Similarly when teaching modern pre-school children, you're supposed to tell them about good and bad behavior -- not try to teach them "you are bad" nor "you have evil", or anything like that, again the subject is various behaviors etc.
But maybe this is just a bit of pedantry on my part -- nit-picking a choice of words, making a distinction that's not worth insisting on -- and not a distinction or a choice of words that I should try to force on you.
And yet, to the extent that "I" have been arrogant and insane myself, perhaps it's a distinction I find helpful -- a "reality check" to try to stop an "ego trip".
But like I tried to say in a previous answer, if you want to see yourself as having an identity that is somehow identical to the Buddha's, who am I criticize, or even to disagree?
It's maybe classically a question of a Middle Way, meaning "neither one extreme nor the other", with "I am unenlightened" being perhaps one extreme, "I am enlightened" being another -- instead the suttas talk about, for example, verified confidence in the three jewels. Confidence, faith, strength, and so on, are important, useful -- maybe the belief that you "have" some enlightenment is more helpful to you somehow, in that way, than it is harmful. I think some people take their confidence not so much from "having" enlightenment but from judging their own intentions, keeping the precepts, generosity too, and so on.
Oh I should mention, the Bikkhuni Sutta -- even if "I have enlightenment" were a form of conceit, the Bikkhuni Sutta implies there's a kind of conceit (like, "if he could do that then so can I") which may be instrumental, necessary:
'This body comes into being through conceit. And yet it is by relying on conceit that conceit is to be abandoned.' Thus was it said. And in reference to what was it said? There is the case, sister, where a monk hears, 'The monk named such-and-such, they say, through the ending of the fermentations, has entered & remains in the fermentation-free awareness-release & discernment-release, having known & realized them for himself in the here & now.' The thought occurs to him, 'The monk named such-and-such, they say, through the ending of the fermentations, has entered & remains in the fermentation-free awareness-release & discernment-release, having known & realized them for himself in the here & now. Then why not me?' Then he eventually abandons conceit, having relied on conceit. 'This body comes into being through conceit. And yet it is by relying on conceit that conceit is to be abandoned.' Thus was it said, and in reference to this was it said.
As for whether it's insane or arrogant, I find the Zen story titled Nothing Exists:
Yamaoka Tesshu, as a young student of Zen, visited one master after another. He called upon Dokuon of Shokoku.
Desiring to show his attainment, he said: “The mind, Buddha, and sentient beings, after all, do not exist. The true nature of phenomena is emptiness. There is no realization, no delusion, no sage, no mediocrity. There is no giving and nothing to be received.”
Dokuon, who was smoking quietly, said nothing. Suddenly he whacked Yamaoka with his bamboo pipe. This made the youth quite angry.
“If nothing exists,” inquired Dokuon, “where did this anger come from?”
Two things I get from that story, one was the youth "desiring to show his attainment" and the other was Dokuon's question at the end, which I think is a fundamental question or purpose of Buddhism -- i.e. the problems of kilesas, how they originate and how to end them -- the anger (on both sides) maybe coming partly from a wounded pride!