What if wishes came true and you knew it? I think sometimes our wishes do come true and we don't know it or acknowledge. Perhaps because they are vaguely worded or, as I call them generic wishes.
You know the kind: I wish it would snow so I won't have work or school tomorrow. And then it does, but not enough to keep you from work or school. But, it did snow, and it is what you wished, so you got one. Or even if you got enough to keep you home that day, what do we usually do? We usually say, ' drat. I have to shovel the stuff'. Which may be why the saying 'be careful what you wish for'.
What if the wish for that A in chemistry had come true and you were heralded for being a chem quiz whiz? And then they discovered you weren't? It was just the wish that made you that way. I will leave the outcome of that in your mind. I already have my version.
On the other hand if every wish came true for everyone, we could be drowning in a sea of mermaids and purple ponies. That would not be fun, because if you are a mermaid how are you going to ride your purple pony?