An anonymous reader sends this quote from an opinion piece at Bloomberg:
"Many programmers find that their employability starts to decline at about age 35. Employers dismiss them as either lacking in up-to-date technical skills — such as the latest programming-language fad — or 'not suitable for entry level.' In other words, either underqualified or overqualified. That doesn’t leave much, does it? Statistics show that most software developers are out of the field by age 40. Employers have admitted this in unguarded moments. Craig Barrett, a former chief executive officer of Intel Corp., famously remarked that 'the half-life of an engineer, software or hardware, is only a few years,' while Mark Zuckerberg of Facebook has blurted out that young programmers are superior."