The world’s largest tech companies further their advantage by building out extensive, global networks to deliver online services to businesses and consumers. This has never been an inexpensive endeavor, but the need for further sophistication and computing power has the bills growing larger each year and there are no signs of a slowdown on the horizon.

Take, for example, the largest three U.S.-based operators of cloud computing services. Amazon.com, Microsoft and Alphabet Inc.’s Google had a combined $41.6 billion in capital...