(Spoilers Extended) Why Ned warning Cersei wasn't an unreasonable risk on his part.

For almost 20 years now, it's been debated to death at this point that Ned confronting Cersei was a stupid move (even though it's far more likely that she already had a plan set into motion before they talked). People who say this act like Ned should've had the foresight to know that Cersei was going to have Robert killed after their conversation, and to that, I say this,

Why on Earth would Ned have a reason to fear that Robert would die boar hunting.

Seriously, what reason did he have? That would've been an incredibly weird thing for him to think. Was he supposed to have a green dream or something where he foresaw Robert getting gutted on his hunting trip? It's not like Robert went off to fight in a war where the chances of him dying are 50/50, no. He simply went on hunting trip in the Kingswood (something that he's done thousands of times) while protected by dozens of soldiers and some of the best fighters in the kingdoms. There was ABSOLUTELY NO REASON WHATSOEVER for Ned to assume that Robert would die in a freak hunting incident. That's not even a plausible thing for him to even consider because there's no reason for him to consider it.

We as the audience know what was going to happen, but the characters in the story don't. Ned had no reason to assume that Robert wouldn't come back in one piece from the hunting trip. That's not stupidity, that's just the worst luck ever.

And let's not get into the fact that Cersei's plan in itself was incredibly stupid and even more risk taking. It was basically "get Robert drunk and hope for the worst." In the words of Tywin Lannister,

I don't distrust you because you're a woman. I distrust you because your not as smart as you think you are.

(edit: On a side note, I feel like a lot of fans who call Ned stupid for his decisions tend to forget one simple thing..........HE DIDN'T WANT TO KILL LITTLE CHILDREN!!!!!!!!!!! Seriously, like, do these people just have no sympathy or morals? Ned truly believed that if Robert found out what Cersei and Jaime had done, he would slaughter their children. I swear, I actually get disturbed by the amount of people in this fandom who think that children deserved to be killed.)