Typically you are granted X number of options. You are never told what the outstanding # of shares are and typically the shares themselves are valued in pennies. The idea is you think to yourself "well, it's 10k shares worth about $5k at the current valuation, but if they IPO and it does what google does...I'll be a millionaire!" You never take in to account that the likelihood of you joining a unicorn like google is near 0% and not taking in to account the time frame of such an adventure, the opportunity cost, dilution and other tricks companies play on their employees before IPOs and acquisitions like reverse stock splits.
And the likelihood of a startup valuation increasing 10x in 4 years (typical vesting schedule) after dilution is extremely extremely unlikely to the point that it is time wasted even entertaining the outcome of such a scenario.