I realize this is still confusing, so here is a concrete example with made-up numbers.
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Netflix offers you stock options that themselves are worth $100, based on various input factors like fair market value of NFLX, interest rates, volatility, dividend yield, etc). Now let's say the strike price of those options is $900. You decided you want all of your $300k/y comp in the form of these options (which are valued each at $100), so you end up with the option to buy 3000 NFLX shares at a later date.
Netflix has a great year (partially thanks to you!) and now NFLX is trading at $1200. You exercise all of your options, buying 3000 for $900 each and immediately selling them for $1200. Net profit: $900,000.
If you'd taken the cash you'd have $300,000.
If you'd taken the cash and immediately invested all of it in NFLX (and then sold them at the same time as the first example), you'd have $400,000.