Zig is kind of a sweet spot for those who prefer the simplicity of C but want something more modern. On top of that it has some cool novel approaches to some things, like comptime for generic programming and custom allocators supported by the standard library that make it interesting enough on its own anyway. Plus,
If you can't see right away why people care, then try asking around (ie any of the Zig communities) for insight on specific use cases. Give it a fair shake and see where you end up.
Asking right off the bat why something is getting popular is basically begging for marketing pitches, plenty of which you can already find on HN on every single thread that mentions Zig:
https://news.ycombinator.com/item?id=37447960
https://news.ycombinator.com/item?id=36996756
https://news.ycombinator.com/item?id=37449994
etc
To give you a more interesting answer, the Zig Software Foundation is a 501c3 non-profit organization (the c3 means that it's tax-exempt, unlike c6 orgs) that pays core contributors, which means we can move the project forward steadfast.
There are also more "subtle" (ie actually very blatant, but people in tech most of the time don't realize how important these things are) reasons that I talk about in the latest Software You Can Love keynote: https://www.youtube.com/watch?v=VJdDdqWmQtk