Conversation so far:
How did Warren Buffett become a billionaire?
Buffett became a billionaire when Berkshire Hathaway began selling class A shares.
When did Warren Buffett become a billionaire?
Buffett became a billionaire on May 29, 1990, with the market closing at $7,175 a share.

Question: How did he feel about his wealth?
Self-contained rewrite: How did Warren Buffett feel about personal wealth?