1) You will spend 10x the time in those 2 years struggling by yourself (or asking questions online). 2) You will have gaps because you missed things 3) You wo

1) You will spend 10x the time in those 2 years struggling by yourself (or asking questions online). 2) You will have gaps because you missed things 3) You won't retain the knowledge as well because you won't be tested on it. 4) If you're someone who isn't good at math, good luck motivating yourself to study real analysis, optimization theory, statistical learning theory, etc.