It's optionality that only has an upside financially, while the downside is just having to do more interviews.

Let's say you're worth 300k on the open market as a senior software engineer. If you get a job that pays 200k a year + 400k in stock over four years, you're making ~300k.

Except if after the first year, the stock goes up 30%, you're making 330k the second year + whatever cash raise you get. Then if it goes up another 10%, and so on... etc.

If, however the stock falls after the first year, presumably you can go out and find another 300k a year job at a different company.