Here's the rub from my perspective.
When we say someone is a "confidence player" it doesn't mean confidence is important to them - that's true of every player - but that their confidence is volatile.
You can have confidence players in a title winning team. You can. But not in certain positions where you need strict consistency. The striking position is absolutely one of those positions.
Havertz may have the physical attributes required to be a striker. He may even have the technical ones. But he doesn't have the psychological traits required. You need someone with bulletproof confidence up front. He's definitely not that.