How can one deal with a father who views marriage as a secondary matter due to economic circumstances, while his son wishes to preserve his chastity?

Filial piety is among the most incumbent duties. If it is possible to combine it with fulfilling the desire for marriage, then that is a good thing. However, if combining them is not possible, and you fear falling into what is unlawful (haram), then marriage must take precedence over obedience to the father. This is because scholars have explicitly stated the obligation of marriage when there is a fear of fornication, provided one has the ability to marry. Furthermore, obedience to parents is conditioned upon conformity with Islamic law.

But if you do not fear falling into something unlawful, and your father disagrees, then try to convince him. Otherwise, obey him, while advising your father to fear Allah and not to impede marriage, which the Prophet, peace and blessings be upon him, encouraged.