Is Hex worth it at high levels?

[JackPhoenix]

The is an awful argument. Here's why:
"Because that's how 5e spells work. If a subsequent action granted by the spell is supposed to be undetectable, it must be somehow indicated in the spell's description."
"There's nothing in Hex's description that placing of the curse is not-noticeable in any way."

2 letters for the first argument, 3 letters and a dash for the second, and they make the opposite case you are trying to make. And what really sucks is all 4 sentences are technically accurate. The spell description doesn't say anything one way or the other. So it's down to ruling and making inferences.

Yes, if you ignore the text in the book and invent your own stuff, you can make the opposite case.