Online, I could be completely cynical about everything, not believe anyone without 10 layers of solid citations, and so on. And to do that I'd have to spend 48 hours per day online checking facts and sources, or never venture onto the internet.
On the other end, I could just believe everyone at face value, and get bamboozled and misled frequently.
Instead, each person has to strike a balance. Have a balance of trust, and recognize when you're putting forth faith in someone. Be ready to transition from trust to cynicism. For things that don't matter (like "believing someone is a millionaire"), don't worry about it - unless and until that "millionaire" tries to offer you personally something too good to be true.