[Zetaphor]

My understanding is around 4 hours, though you don't lose your entire stake, you pay a small penalty, determined by the current health state of the network. Slashing as most people think of it is reserved for malicious activity like contradicting network state.

It's worth saying that you shouldn't consider running a validator unless you have the commitment and skill to maintain uptime and availability. This is a reward for skilled labor, not a "set it and forget it" revenue stream. It's your responsibility to ensure your client is up to date and operating correctly.

While that doesn't necessarily mean you're chained to doing frequent maintenance, it's also not something a casual user should be doing without knowing what they're doing. Fortunately this information is widely available for anyone willing to learn.

Work is being done on light clients which will bring us closer to the average consumer being able to contribute to network decentralization with a low effort contribution of hardware access, but today this is an operation where participants are responsible for high availability services with real financial stakes.