Every single PhD Mathematics program I've ever heard of covers full tuition and provides a stipend for the full period of study for the vast majority of its stu

Every single PhD Mathematics program I've ever heard of covers full tuition and provides a stipend for the full period of study for the vast majority of its students -- it isn't particularly generous, but it's livable if you're willing to be frugal and focus on your work. The problem is the opportunity cost of someone with mathematical capacity at a doctorate level barely breaking even for 4-6 years before they even begin their career.