Does the belief that one should prioritize the performance of Sunnah and voluntary prayers over what one deems better for one's livelihood and bodily health, based on the understanding that whoever believes there is guidance better than that of the Prophet commits an act of disbelief (kufr), render a person a disbeliever?

The belief of the Ahl al-Sunnah wal-Jama'ah (Sunnis) is that whoever holds the correct belief, performs the obligations, and abstains from prohibitions will enter Paradise. The statement of scholars, "Whoever believes that there is a guidance better than the guidance of the Prophet, peace and blessings be upon him, commits an act of disbelief (kufr)," refers to religious matters, not worldly ones. So, whoever believes that there is a religion, a method of worship, or a path to gaining Allah's pleasure better than the Prophet's law (Shari'ah) is a disbeliever. As for permissible worldly matters, there is no harm in them as long as they do not fall into what is forbidden, knowing that the Prophet's guidance in everything is the best. A Muslim can transform habits and permissible matters into acts of worship with a righteous intention, such as seeking knowledge with the intention of benefiting oneself and others, and engaging in sports with the intention of strengthening the body for worship and helping people.