One person's dystopia is another's Christian nationalist authoritarian paradise. Vought / Project 2025 have been quite explicit in their goals. They believe that they're at war with secular institutions and what they call the "administrative state" - any government function that operates independently of direct political control by the executive branch. That is an explicit goal of doing away with the US Constitutional system. Vought has justified this through conspiratorial nonsense, claiming that the "deep state" has already brought about a "post-Constitutional" order via bureaucratic overreach.
Their plan will mean impoverishment of most of the population, as well as removal of a substantial part of the population through deportation but they're not particularly concerned with that. In their eschatology, non-believers (which includes not just atheists but Catholics, Jews, Muslims, and even other Protestant denominations they deem insufficiently pure) are literally destined for eternal torture in hell. Some of the more extreme elements actively look forward to this as divine justice. Their apocalyptic worldview frames everyone outside their narrow in-group as either potential converts or enemies destined for damnation. Why worry about climate change, democratic institutions, or social welfare when the faithful will be raptured away while the unrighteous suffer? This theological framework makes it remarkably easy to dismiss the suffering of others as either deserved or irrelevant in cosmic terms.
Musk has a different set of motivations. Some of it is just straightforward corruption - killing off agencies and firing specific individuals who have pushed investigations of his various enterprises, as well as awarding contracts to himself (e.g. the FAA Starlink contract, which is genuinely terrifying).
But as far as his motivations to decimate government more generally, I think it's a combination of things. He seems to genuinely believe that dismantling government oversight will unshackle great men such as himself to bring about some techno-libertarian utopia. But I think a lot of it is that his brain has just been pickled by right-wing social media and he's a bit of a useful idiot. The fact that this aligns with Christian nationalist goals is just a convenient overlap.
Then there's the Stephen Miller wing, who are primarily motivated by racism (of course, all of these factions are extremeley racist).
It's all quite grim.