Gig companies are the 21st century robber barons.
However, Uber and other companies did start right after the dot-com recession, when people needed to both save money, and make extra money. It turns out a lot of people needed to do both. Sure, there were advantages over the previous incumbents (cabs suck), but that's not why there are so many drivers.
Ask your Uber or Lyft drivers sometime how often they work. Many of them, since the early years, told me they work as many hours as they can, for as many companies as they can, just to make ends meet. Of course they're paying for their car and all that themselves, too, so it's not like they're getting ahead. And they definitely would rather not be driving for 14 hours a day.
These companies exploit people in an unequal system in order to make profits.