Indeed an interesting dilemma, particularly since you are half way rather than just 2 years to 10 years. If you have not any business travel foreseen, it is spending a bit over 3000 CHF on mileage runs for 5 years if the options BubbaX indicates stay around. But there is a number of risks
- such cheap mileage run options disappear. Could be hedged by doing them quickly (but implies spending say 10000 CHF this year.....)
- FB raises the bar for Platinum to well over 300 XP (or lowers the XP per segment)
- There is another major overhaul of FB leading to different qualification schemes, PFL is abolished (either totally, or just closed for new entrants), etc.
- AF/KL goes bankrupt or is taken over, and with this FB disappears.
- Climate policy really becomes serious making flying very expensive and, like in the 1960s, again only accessible for the jet set.....

One additional factor coming into play may be your age. If you are young, you can benefit long (assuming PFL stays and AF/KL stay, and it makes sense for you to keep them as your preferred airline). If you are older say about 60 (since you are a student I guess not applicable), 10-15 kCHF can give you for a lot of years a Priority pass or some expensive credit card, that allow for lounge access and other benefits.......you then only miss the free Economy comfort, but that is only KLM and you can pay for such seats.