Midfielder De Guzman, who represented Netherlands in this summer's World Cup, suggested that he led with his heart and not with his wallet by opting to turn down a more lucrative offer from Rangers to move to Serie A.
He told Dutch newspaper Algemeen Dagblad: "On the table there were two offers, one from Napoli and the other from QPR.
"The English side's one was the most important and Villarreal would have liked to sell me to the best offer. But I wanted Napoli and in the end my will decided the negotiation."
De Guzman, 26, scored 15 goals in 93 appearances during two consecutive season-long loan spells at Swansea and helped the Welsh outfit to their first major trophy - the 2013 Capital One Cup.