It's easy if you try. It's possibly to edit the HTML of any website easily, one doesn't even have to use Photoshop any more. PayPal displays the balance multiple times, showing that all are the same make a naive mind more hopeful this isn't fake. Taking a photo of a fake screen is a more complex process than just photo-editing a screenshot, making the more naive fall easier..
Once you realize these points, hopefully you'll never allow anybody to trick you into revealing your PayPal email etc. address, you silly person.
I made a mistake in this example. Can you spot it?