Peter Elkind, Patricia Sellers, and Doris Burke comment about investor and Texas billionaire Richard Rainwater’s incurable brain illness in Fortune:

PSP [Progressive Supranuclear Palsy] is a fast-moving, degenerative brain disease, with no treatment and no cure. The typical life expectancy from diagnosis: 4 1/2 years. “In the world I live in,” the doctor told Rainwater’s friends and family, “this is the worst disease I see.”

Of all life’s cruelties, it seems especially tragic that Richard Rainwater would suffer from this affliction. Rainwater is a self-made billionaire, a Texas incarnation of the Horatio Alger story. But he hasn’t built a chain of discount stores or a computer company or even a private equity firm to leave behind. No, Rainwater’s business genius has always been his energy and imagination—his uncanny ability to see where the world is going and find a way to exploit that turn. It was his personal magic that made big deals happen: his ability to pick the right opportunity, the right partners, the right CEO, and then to provide inspiration. The billion-dollar edifice he built was all in his head.

And now it’s crumbling away.

Today Rainwater requires 24-hour care. He is unable to walk unassisted. He has trouble swallowing. His speech is almost impossible to understand.