Mr. McCaleb has since created a competitor to Ripple, known as Stellar. Stellar has risen even faster than Ripple in recent weeks, with all outstanding Stellar tokens — known as Lumens — worth around $14 billion on Thursday, making it the seventh largest virtual currency.

In contrast, all the outstanding Ripple tokens were worth $140 billion on Thursday, while all Bitcoin were worth $250 billion.

Yet the fortunes of Mr. McCaleb and Mr. Larsen are not nearly as durable as those of other people on the Forbes list given that the value of virtual currencies fluctuates wildly. If Mr. Larsen wanted to access his wealth by selling Ripple tokens for dollars, it would likely drive down the value of Ripple tokens — and his riches.

Mr. McCaleb and Mr. Larsen did not respond to questions about the recent price increases.

Mr. Larsen was Ripple’s chief executive from 2012 until he stepped down last year to become the company’s executive chairman. During his tenure, Ripple focused on helping banks use its software to shift money between different foreign currencies, something that most banks currently do through a cumbersome process involving separate accounts in every country where they operate.

Ripple has said it has signed up more than 100 banks to use the company’s technology, including American Express and Banco Santander.

But banks do not need to use Ripple tokens for Ripple’s software to transfer dollars, euros and yen. That point appears to be lost on many small time investors who are buying Ripple tokens.