My fav manager had a great way of phrasing this: "There are more ways for your options to be worthless than to make you rich"
But I also personally know plenty of people who made off great with their startup equity. They're def not worthless.
Ultimately I think you should never take an uncomfortable pay-cut to join a company and you should maximize your stock compensation on top of that. Don't forget other types of equity – brand, exposure to good problems, network.