And this children is why you never ever discuss new and novel things with third parties (or even particularly widely) if you either want to patent them yourself or don't want someone else to steal them.
Throwing the idea into the public domain can work as a spoiler but it's a wasteful approach if you're the sort of person who actually needs an income to survive; they can still steal your idea and steamroller you with their product, they just can't patent it. Well, actually they can patent it but they're vulnerable to prior art claims.
Without an NDA discuss nothing. With an ironclad NDA discuss the bare minimum.
And when you eventually put an idea out there make sure you cover *all* the possible expansions of it even if you never intend to go there yourself. It really limits the opportunities for people to piggy back off your work.
And a proper technically minded patent attorney is worth the cost.
And another point - if you think somewhere wants to hire you, make sure you don't let them harvest your brain until *after* you're employed and getting paid. Spilling all the beans during the interview can let people get all they want for free.