The 555 timer is still the most popular chip that hobbyists add to their parts inventory (see rankings at https://partsbox.com/ecdb.html). I find this both interesting and curious — I'd say it has mostly nostalgic value at this point. Almost every practical problem today is better solved by something else. And yet it persists, I guess mostly because of beginner tutorials and first LED blinky circuits.

One nice thing about the 555 is that at least it aged well and still is very usable in those beginner tutorials. Unlike for example the uA741 which no one should use.