COTATI, Calif. — Uber’s public stock offering next month will make a bunch of people remarkably rich. Peter Ashlock is not one of them, although he has toiled for the ride-hailing company almost since the beginning.

Mr. Ashlock, who will be 71 next week, has racked up more than 25,000 trips as an Uber driver since 2012. His Nissan Altima has 218,000 miles on it — nearly the distance to the moon. His passengers rate him 4.93 out of five stars. His favorite review: “Dude drove like a cabdriver.”

While he is an integral part of Uber’s success, Mr. Ashlock is barely getting by. His 2018 tax return will show an adjusted gross income in the neighborhood of $40,000, better than 2016 and 2017. But he has maxed out his $3,200 credit limit at the local Midas car-repair shop and needs to come up with $5,000 to pay his taxes. He has Social Security but no savings to buy a new car that will let him keep working.

Silicon Valley has always been a lottery where immense wealth is secured by a few while everyone else must hope for better luck some other time. Rarely, however, has the disparity been on such stark display as with Uber. Its stock market value is expected to be about $100 billion, which would make it one of the richest Silicon Valley public offerings of all time.