Success in maths (soft question) I would really like to hear from any professional mathematicians who didn't just sail through their university education. If one looks at the pages of many of today's mathematicians, one finds that they usually aced their university exams (often coming top of the year at prestigious universities etc). This can be disheartening (at times) for someone who hasn't followed that path. Is there actually a non-negligible hope for such people? Thank you.

Rob Kirby may be the example you are looking for (https://www.simonsfoundation.org/science_lives_video/robion-kirby/):
In 1963, rising mathematical star John Milnor set forth a list of what he considered the seven hardest and most important problems in the nascent field of geometric topology. Just five years later, no fewer than four of those problems had been laid to rest, largely through the efforts of a young mathematics professor whose entry into mathematics research had seemed anything but auspicious. Described by colleagues and students as “slow,” “non-threatening,” and “deliberate,” Robion Kirby had followed a desultory path through higher education, marked by failed exams, lost fellowships and recommendations that he go study somewhere else. Yet just three years out of graduate school, he pulled off a mathematical coup, one that helped define the future of his field.
“I sometimes felt like the Virgin Mary,” Kirby says. “How could this happen to me?”

Another example (coincidentally also in topology) is Stephen Smale: https://en.wikipedia.org/wiki/Stephen_Smale
Smale entered the University of Michigan in 1948.[3][4] Initially, he was a good student, placing into an honors calculus sequence taught by Bob Thrall and earning himself A's. However, his sophomore and junior years were marred with mediocre grades, mostly Bs, Cs and even an F in nuclear physics. However, with some luck, Smale was accepted as a graduate student at the University of Michigan's mathematics department. Yet again, Smale performed poorly in his first years, earning a C average as a graduate student. It was only when the department chair, Hildebrandt, threatened to kick Smale out that he began to work hard.[5] Smale finally earned his Ph.D. in 1957, under Raoul Bott.
