Upvoted for clarity and relevance. You touched on the exact reason why many people I know can't/won't become EAs; even if they genuinely want to help the world, the scope of the problem is just too massive for them to care about accurately. So they go back to donating to the causes that scream the loudest, and turning a blind eye to the rest of the problems.

I used to be like Alice, Bob, and Christine, and donated to whatever charitable cause would pop up. Then I had a couple of Daniel moments, and resolved that whenever I felt pressured to donate to a good cause, I'd note how much I was going to donate and then donate to one of Givewell's top charities.