Dennis graduated in 1998 with an MBO qualification in Retail from Horizon College in Hoorn. At the age of twenty-two, he took over his parents’ bookshop. He always enjoyed working with numbers, particularly handling administration and purchasing. After twenty-five years in the business, he was ready for a change. He sold one of his two bookshops and joined Team V, where, since 2024, he has been responsible for invoicing and fee administration as Leo’s right-hand man.