Imagine it's 1851, and you're sick and tired of waiting for the Pony Express to deliver important messages. You happen to meet a Mr. Morse and buy into his idea for using copper wire to send instant messages over great distances. Your friends laugh, telling you to get a real job—wires are silly things for grown men to play with. At great financial risk, you build the first cross-country cables in the U.S., and it works, changing the world. Your organization thrives for years; the nation is communicating, for a price, over your cutting-edge digital communication network. Wealthy and famous, attractive people soon throw themselves and their money at you. But you're not finished: in a fit of innovation, you create the first stock ticker in 1866, give the nation its first standardized time service, and revolutionize the financial world with money transfers—allowing people to send cash thousands of miles across the country in seconds.
In the middle of your glory, as your rise to innovation fame reaches untold heights, a young man visits you. He holds an odd machine in his hands. He claims it will replace everything, especially all the things you've struggled all your life to build. He's young, arrogant, and dismissive of your achievements. How long would you listen before you threw a telegraph at him? Could you imagine, given all you'd built, that something as simple as his clunky wooden box would replace everything you know? Or would you have the guts to give up the innovations you'd made and put everything behind the unknown?
This challenge of mind is known as the innovator's dilemma. The face off between Western Union and Alexander Graham Bell (dramatized but roughly accurate in my telling) has been played out for centuries, with the captains of one aging innovation protecting their work from the threat of emerging ideas. The concept is well described in Clayton M. Christensen's book, The Innovator's Dilemma, which provides hearty business examples of faith in the past blinding smart people from the innovations of the future. 
It's both a psychological and economical phenomenon: as people and companies age, they have more to lose. They're not willing to spend years chasing dreams or to endanger what they've worked so hard to build. Attitudes focused on security, risk aversion, and optimization of the status quo eventually become dominant positions, and even become organizational policy at companies that were once young, nimble, and innovative. Even its success enabled it to grow into mainstream businesses, diminishing their interest and capacity for new ideas.
For these reasons, it's rare in art, music, writing, business, and every single creative pursuit for innovators to sustain that role throughout their lives. It's not that their talent wanes, it's more that their interests change. Having succeeded, their strongest desire is not to find new ideas to conquer, but to protect the success they already have.
 Clayton M. Christensen, The Innovator's Dilemma (Harvard Business School Press, 2003).