Why are so many automakers, tech firms, components suppliers and ride-hailing companies pouring billions of dollars into developing self-driving cars and trucks?

In part, it's because the payoff could eventually be worth $7 trillion.

That's the estimate of a new study from the research firm Strategy Analytics and Intel, one of several tech giants investing heavily in autonomous-drive systems.

"This technology is driving big changes," said Kathy Winter, vice president and general manager of Intel's Automated Driving Group. "Time will be freed up by people not driving, there will be increased productivity and new goods and services to be consumed."

The study predicts a global "passenger economy" will start to grow after the first fully autonomous-drive vehicles hit the market in the next four to five years. At first, there will not be many, and their use will be limited, but by 2035 Intel expects the passenger economy will climb to $800 billion worldwide.

In 2050, Intel estimates, the global passenger economy will be worth $7 trillion. While it's too soon to know which companies will profit the most from the new world of transportation, Intel estimates the money will come in three primary areas.

$3.7 trillion from consumer mobility-as-a-service

Includes: Vehicle car-share and ride-share companies.

Includes: Vehicle car-share and ride-share companies. $2.9 trillion from business/business-to-business mobility-as-a-service.

Includes: Freight and self-driving delivery companies.

Includes: Freight and self-driving delivery companies. $203 billion from pilotless vehicle services

Includes: Consumer businesses like restaurants, health-care providers, entertainment companies.

Initially, many of the autonomous vehicle services and benefits will be found in cities and suburban areas with large populations. However, analysts believe self-driving vehicles will also reach rural areas.

"There are probably people in a rural area who have as much of a need for autonomous-drive vehicles as someone in a city," said Roger Lanctot, director of automotive connected mobility in the global automotive practice at Strategy Analytics.

While the dollar impact of the coming passenger economy is huge, the other benefits of widespread adoption are enormous. For example, Intel estimates pilotless vehicles will save at least 585,000 lives between 2035 and 2050.