I think the biggest reason for this is because Silicon Valley has an abundance of younger workers (relatively speaking). When you're young, you spend literally every moment working to strive for your ambitions. When I got older, I started to learn that every hour you spend at work is one less hour for you to spend on something meaningful to your personal life. At the end of the day, working long hours is just not worth it. There's literally nothing to show for it at the end of the day. You make less per hour. Your family hates you. And you have no personal life. The only people that really benefit from this mentality is the owners and investors and this is so unfair and toxic to the workers.