Jamie Dimon has been a vocal critic of how much the nation, especially employers, pay for health care. The J.P. Morgan CEO has teamed up with Berkshire Hathaway CEO Warren Buffett and Amazon CEO Jeff Bezos to form a joint venture aimed at tackling health-care costs. The trio hired Dr. Atul Gawande to lead the venture. The group is now focused on hiring a team, Dimon said.