The 2025 refers to the year he'll graduate - it's fairly common for US college students to classify themselves this way - and this is a college publication he's being profiled on.
Consider “class of 2025” as shorthand for “cohort targeting 2025 graduation” if you are struggling to accept it :)
Are there many Dutch university students who don't graduate?
In the US at least, the 4-year graduation rate at e.g., MIT and Harvard are well above 90%, quite a bit higher than the national average.
- You decide to divorce your partner based on circumstances you weren't expecting.
- Your partner decides to divorce you.
In the analogy, those would correspond to you leaving the school, or the school expelling you.
But the element of "circumstances you weren't expecting" has been completely lost. There's nothing more predictable than the university experience.
Are 30% of Dutch undergraduates leaving because they stumbled into better opportunities? Are they leaving because they're surprised that "school, but more of it" feels like more school? Are they leaving because their schools find that they perform below what their credentials suggested? (And if it's that last one... thirty percent?)
That divorce question was a shorthand way of saying that not everything that you plan to do ends up running to completion. In general I think the answer is 'life happens' and not everything you start gets finished. People get disillusioned, they might see the future of the field they started to study in as imperiled or they might simply find that they do not see an advantage to completing the study. They might not have the self discipline to complete the run or they might have other needs or changing circumstances. They might simply get ill. They may find an opportunity that short-circuits the need for a degree.
Lots of people do graduate but to assume up front that over a period of four years of someone's life things are so stable that you will always be able to graduate is to ignore the reality of the circumstances of a large number of people.
At US “elite” schools there is definitely an expectation of completion in 4 years, though not much stigma if you take longer—and students go through in cohorts with target graduation dates (“class of ‘25” or whatever).
In Germany or Austria, it would also be considered absurd to prematurely declare yourself a “future graduate of (today + 3-6 years)”.
One reason for that is people dropping out: Changing your major is not really a thing so you need to start over or you at least only get partial credit and need to add some semesters if you do. There’s also very little preselection of applicants, so many only realize that they don’t like their major or don’t have the skill set/motivation/grit to still finish it halfway through or later.
And for those that do graduate, there is very little incentive to actually graduate on time: Tuition is free, and many people trade speed for work experience while studying (or just to support themselves at a nicer lifestyle than just a students budget; taking on student loans is not that common either).