<p>It’s partially true, in the sense that basic analysis and algebra (groups, rings and fields, not symbolic manipulation) are proof-based courses, and not “computation/quantities” based like calculus and high school algebra. That can be a shock for many, though a few find it quite natural. The attrition rate in the first year of math is pretty high, because mathematics is not what many expect it to be for those who come unprepared. But if you have a passion for math I wouldn’t be too worried, except that your passion may be “challenged”, so to speak.</p>
<p>Pure math gets really abstract, and not everyone is quite prepared for just how weird and counter-intuitive things can get. However, once (if) you survive the shock, it’s usually not that bad, and then you have a wide variety of options, from the very pure to the very applied, and a strong theoretical base will help you conceptualize a lot of things abstractly and should give you good problem solving skills, as long as you keep in touch at least with the “real”, application side. I also recommend (in places where it’s not required still) for all math majors to take a few computer science courses (basic programming and algorithms).</p>
<p>How bad was it for myself? Well, my GPA dropped from the A/A+ range in high school to the B range in my first semester (with a C in Analysis I, that hurt, then again, I had 21% in the first midterm, though the prof said to the class, before handing them back “no, it’s not out of 25”), and I worked a lot more than in high school (really, back in high school, all I needed to do was to attend classes and pay attention to get A+, no studying necessary). My GPA slowly climbed back up over the years (I almost had a straight A semester in my last year), ending in between B+ and A- overall (slightly closer to the latter). I did go away from pure math (my original intent) more toward applied math and statistics, and ended up doing a PhD in stats (though in my bachelor, I had more applied and pure courses). I found the later courses much more interesting, and realized also some of those dry theoretical courses I had to go through at first would “pay off” later on.</p>