Business is booming for investors in college housing, who poured $22.9 billion into the industry last year. But for students, the picture is more fraught.Tyler Le/InsiderWaterloo, a 30-story tower just a few blocks west of the University of Texas at Austin, has everything the modern college student needs: Its top floor features an infinity-edge pool, a pair of saunas, and a yoga studio, while the lobby includes an in-house coffee bar and ample nooks and tables for socializing or studying.