In the Netherlands (and all other countries), many costs are incurred every year for training, competitions and materials. In America, all these costs are covered by the university, this is the reward that athletes receive for playing for the university team.
Universities are often sponsored by major brands such as Nike, Adidas, Under Armour, etc., which means that you do not incur any costs for (sports) clothing. Services such as physiotherapy are also included in the package of a student athlete.