Guess what? The vast majority of them never will use algebra in real life. Most jobs simply don't require it.
Then you don't understand algebra. Everyone uses algebra, whether they realize it or not. E.g. You are at the supermarket and you see milk is on special: "Get two for $5.00." Most people can figure out that one costs $2.50. In other words, 2x = 5, solve for x.
I will, however, agree that most people never learned it well enough to use it for anything more complicated. Your comment proves my point: "When you don't understand something, it's easy to say it has no purpose".
In 1996, I developed Exuberant Ctags as a better ctags. Bram started including it in his Vim distributions and our programs were paired together in much the same was that Elvis was packaged with its own ctags clone, and Emacs was packaged with its own ctags. Eventually, Exuberant Ctags became large enough that it caused the Vim distribution to become too large to fit on a 5.25-inch floppy and Bram said it was time to let them grow separately. Exuberant Ctags, as well, got picked up by the Linux distributors as the resident ctags program.
I have always enjoyed working with Bram over the years and wish I could have met him. He is a very pleasant and easy person to work with, very accommodating, and very bright. I think very highly of him and I am glad to see his editor become one of the bulwarks of Linux distributions, as well as used on many other platforms.
"Necessity is the mother of invention" is a silly proverb. "Necessity is the mother of futile dodges" is much nearer the truth. -- Alfred North Whitehead