That's not true.
Your mileage will vary.
Of course it will. Of course everything won't be precisely as you imagined it, as it was described, as you deserve.
Sure, then what?
Will you react or respond? You could react in anger and fear. You could find people to blame, you could easily amplify your anger, you could dig deep for vitriol and snark and use your words and actions to drive a wedge between you and whoever didn't meet your imagined spec.
Or, perhaps you will respond by focusing on the opportunities the divergence presents. What a chance to celebrate what you've got and even better, find a way to build something even better.