I am a student too. I have a part-time job in addition to the monthly 350 euros I get from the government. Also, living with my girlfriend helps keeping the living expenses down.
While running a car is damn expensive, it's cheap compared to the public transport system and the time consumed utilizing it.
A month's pass costs around 100 euros, and by bus, oneway trip to work or school is 50-60 minutes. I drive to those places in 10-15 minutes.
If I set a price for my "work" of standing (in the rain) and waiting for a bus (~5-10 minutes per trip) around 10 euros/hour, the 40-50 trips each month amount to 400-500 euros worth of personal boredom and lost time each month.
On the other hand, driving to school and work is often a thrill. Plenty of nice corners and places to overtake slower vehicles.