All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Hajj is obligatory for the legally commissioned person who is financially and physically capable, as Allah says in the Quran: "Pilgrimage thereto is a duty men owe to God,- those who can afford the journey." {Al-Imran, 97}. Financial capability means that an individual possesses the financial means to undertake Hajj, including the cost of travel, accommodation, and other necessary expenses, without compromising their essential needs such as housing and sustenance. As noted by Sheikh al-Islam Ibn Hajar al-Haytami, "Capability... includes having the necessary provisions and supplies for the journey, as well as the means of transportation." {Al-Menhaj al-Qawyem Shareh al-Mokhadimah al-Hadramiyah, Page 270}.
The prioritization of Hajj and other matters should be based on individual need and necessity. Although Hajj is an obligatory act of worship, it is also flexible in terms of timing. Sheikh al-Islam al-Nawawi stated: "If someone possesses surplus wealth and is in need of marriage due to concerns about moral issues, it is more important for them to allocate their resources for marriage than for Hajj. This is justified by the urgency of the need for marriage compared to the flexibility of the Hajj obligation." {Rawdat at-Talibeen, Vol.3, Page 7}. It's important to consider individual circumstances and prioritize accordingly, as people's natures, customs, and needs can vary.
Regarding having a child, there is no doubt that it is one of the major purposes of Islamic law in preserving the lineage. However, it's something that can be delayed, especially if the wife is still young.
In conclusion, indeed, Hajj is one of the pillars of Islam and a significant act of worship that should be pursued because Allah the Almighty says {What means}: " then strive together (as in a race) Towards all that is good." In other words, "You should initiate and hasten"{Al-Baqarah, 148}. However, it is also an obligation that can be delayed. Therefore, when there is a conflict between different priorities, the principles of Islamic jurisprudence regarding prioritization should be applied. And Allah the Almighty knows best.