I'm asking this question mostly looking for advice as a student, but I also thought this could be an interesting discussion subject for this SE comunnity.
A word of explanation first: I'm a first year undergraduate student of mathematics in Poland, and the "program" is organised so that before the start of the 2nd year one chooses in what "aspect" of mathematics they want to specialise. There's stuff like theoretical, applied, mathematics in economy and some other things I'm not really considering. Based on the specialisation chosen, you're going to be attending a certain set of classes until the end of the undergraduate stage.
Now, theoretical mathematics is definitely the most interesting one for me, but at this university it's also by far the hardest specialisation. In previous years, it got about ~12 of the best students total, out of over 100 in other specialisations and the classes one takes after choosing are indeed very demanding. The question is, how beneficial would it really be to choose something this demanding. The way I see it, it certainly has a lot of benefits, attending difficult classes with the best students in the given year would certainly be very educating. On the other hand, it'd be very time-consuming, leaving little place for one to keep learning additional things, outside of the standard curriculum.
How much does a student actually benefit from attending classes at a significantly higher level than normal, at the expense of their freedom in choosing what branches of mathematics they could study on their own(which would be possible if an easier and less time-consuming specialisation was chosen)?