I can start a new project that relies on Make, and be extremely confident that Make will continue to work and be maintained for the lifetime of my project. 20+ years from now, Make will still work. My Make knowledge will be relevant for my entire career.
New and shiny replacements like Just are tempting, but you have to consider the real cost of:
1) Learning a new build system
2) Onboarding new devs with an unfamiliar build system
3) Dealing with the eventual deprecation of the new shiny, once something newer and shinier comes out. Rewrite your build scripts, GOTO 1.