"It does create a rising price, creates more buyers ... If you don't understand it, you get much more excited," Buffett said on CNBC television. "People like to speculate, they like to gamble."
The purchase initially sent share prices soaring by 12 percent.
Buffett's comments come a day after JPMorgan & Chase Chief Executive Jamie Dimon said he regrets calling bitcoin a fraud.
The billionaire business magnate is said to own $5 million of Israeli bonds in his personal portfolio.
Why not think about doing for our people what Buffet and Gates are doing in the general philanthropic world?