I'm not saying Math is useless, I'm saying there must be tiers for topics in how useful they are such that someone can say "Hey, that's pointless!" and one can't follow with "Therefore all things are pointless". Or, that allow me to rank niche topics in their usefulness.
Irrigation is very important. Now, is Irrigation Maths more important to us as a species than Terrence Taos work on spontaneously combusting water? Probably! Would it be more useful to have PhDs be funded in optimizing food routes between countries after climate change over game theory applications for blackjack? Probably!