There are lots of stipends etc. If you don't plan to have kids, and you don't care about luxuries, you will have healthy food and a roof and not be thinking about money. Probably the decision is to forgo luxuries and child raising, and hope you don't need to help a sick relative etc. if you want do to this forever. But it is not impossible in STEM.

That works as long as you don’t expect to graduate: in many EU nations, higher education students are required to complete at least 60 ECTS credits per year, or lose their study right / enrollment.