How do you practice with them?
Finally I realized it is nothing more than the power of belief.
Yes, the power of belief can be very strong, but as many (including Crowley himself) have pointed out -- you cannot make a silk purse out of a sow's ear.
The person receiving the reading "makes" the reading "real" simply by believing it so.
But, once we realize this, we can see the fake magic in other things. Like the magic of the badge which police wear. Or the magic of hierarchy, position, status, and public office. Laws, authority, obedience, domination and submission.
The person reading the cards can tell us nothing we don't already know, and those in power have no power beyond what we give them.
It's all fake.