It took Amazon 14 years to first show a profit on their books. Some VC's are interested in scalability and revenue growth and aren't looking for a short-term return.

There's a story about some popular artist Mark Zuckerberg hired to paint a mural in FB's office many years ago. The artist got paid in FB shares instead of cash. His stock value ended up being well over $100M due to the rapid rise in share price in the following years. So, yeah, VCs and common investors are taking a long-term gamble and will continue to fund a company as long as they show sustainable growth.

UE spends a ridiculous amount every day on advertising and attempts to take away customers from their competitors. Years ago, Uber itself spent a fortune researching and building self-driving vehicles. They have since abandoned that project but partners with other companies continuing their research and development. This costs a ton of money where no one has reap any immediate benefits. Investors are confident that Uber's efforts will pay off eventually so they'll continue give them their money.