SpaceX's advances are one of the biggest sources of excitement about humanity's future for me.
And an O'Neill cylinder large enough won't cause vertigo.
But we are nowhere near to even realistically plan on achieving something like that
So then humanity could pool together all resources to operate moon habitat and space industry to create space megastructures... then yes its 'achievable'
A Kalpana One space habitat is estimated to require a mass of 10 billion kilograms, or 10 million tons.
One Starship launch can place 100 tons in orbit. 10,000 Starships, launching once a day, can place 10 million tons into orbit in 10 days.
From there, tapping extraterrestrial resources becomes far more feasible, and using them to construct an O'Neill Cylinder comes within sight.
Sources:
Peter Hague's Planetocracy blog provide the Kalpana One mass estimates: https://planetocracy.org/
Starfactory planning to manufacture one Starship per day: https://www.space.com/spacex-starship-one-a-day-starfactory
Space exploration has already spurred significant technological advancements and I anticipate that space colonization will catalyze orders of magnitude more innovation.