As always, context matters.<p>Legal and ethical obligations aside (it is illegal in most places, and unethical everywhere [1]) there are (mostly bad) reasons for discriminating based on age in some places.<p>First though it's worth pointing out that the industry as a whole is young. When i started in the 90s everyone was young. Most businesses didn't have a computer at all. A generation of 90's kids went round writing software, selling computers, building networks and so on. There were -very- few old, experienced folk from the mainframe era floating around.<p>Today we're in our 50s, so at least we exist, but we're still swamped by folks who started this millennium.<p>So first problem is that most startups (founded by youngsters) probably encounter a lot more youngers than olders. Since the goal is to get-rich-quick, it seems counterintuitive to hire others who haven't done that.<p>Secondly, as people develop their careers they slowly stop job-hopping. Most folk in their 50s have found their home. Especially if they're good. So (consulting aside) startup jobs are not that attractive. Cheap pay, long hours, opionated (inexperienced) founders, isn't overly attractive to me.<p>All of this plays into the idea that "its a young person's game". Which of course is nonsense. We stood on the shoulders of those who went before, and the systems of today stand on ours. The folks who built Unix and Cisco, HP, and so on were all previous generation. Today the people who built the internet are over 50.<p>The valley may like to discard the old, because they remind us that the VC model mostly spits out failure. But outside that bubble companies mostly value stable, experienced, quality "old folk" who want to provide real value, not scratch lottery tickets.<p>[1] Ethics are subjective, but we're all getting older, so you might want to sow good karma while you're young.