It’s best to value the options at $0 and consider them a lottery ticket.
The company is very transparent with the numbers, though. Every month we have an all-hands meeting and the CEO goes over numbers, including current ARR, burn rate, balance, and runway.
We received a $75M Series C in May, and in our last fiscal year we 4X'd our ARR. We're doing pretty well.
When things go badly, or even just not well, it doesn't matter what your plan was or how transparent everything is - the founders/board may be staring down a choice between folding the company up or decimating the equity of everyone currently holding it. It's a pretty easy decision usually. The good ones will take it on the nose with everyone else, the others ... well they aren't taking the same hit.