Most asteroids are worthless chunks or carbon, another significant portion are sort of dirty balls of sand and rock. The smallest portion are composed of any metals. Metallic asteroids are mostly iron and nickel and unlikely to be loaded up with precious metals. Any that would be interesting for mining would be in the asteroid belt which requires significant amounts of energy to reach in a reasonable time frame.

You also don't seem to be aware, Ceres does not currently have a space gas station on the surface. If you intend to refuel and resupply there such a thing would need to be build...for hundreds of billions of dollars because it's super difficult and none of the technology to do it currently exists. So that would need to be invented, developed, built, and put into space.

Also raw ore amounts don't mean anything without refining capacity. There's roughly zero of it currently anywhere off the surface of the Earth. Again, in-space ore refining is something that exists pretty much only as concept drawings and some PhD thesis. So that would need to be invented, developed, built, and put into space.

Even if we could reliably get people out to the asteroid belt and keep them alive, the volume of the belt is absolutely enormous. Worthwhile asteroids are vast distances apart and far away from any larger asteroids you might want to use as bases. It would require enormous expenditure of resources to get some mining equipment to a worthwhile asteroid, mine it, and get that raw ore somewhere it could be processed.

The lack of gravity and atmosphere makes space mining far far more difficult than mining on Earth. If you kick up dust on Earth it blows away in the wind or settles quickly. Kick up dust on an asteroid and it goes into orbit around it and takes potentially centuries to settle. Asteroid dust also has no weathering so it would be extremely harsh on all the equipment. That all just makes the venture more difficult and more expensive.

Then you've got some iron and nickel, something the Earth literally has tons of. Even if you manage to find the Comstock Lode asteroid you'll spend billions to mine precious metals which will cease to be precious thus lose their monetary value.

The differences between crossing the Sahara to find gold and looking for it in an asteroid are when you cross the Sahara there's air at the destination. You don't have to make the crossing in a tin can containing your own personal universe. At any point along the journey you can take a deep breath. If you tear your shirt you don't suffocate and die. If you trip and fall you don't float away unable to be recovered. If you drop something important it lands on the ground rather than float away never to be seen again. A solar flare isn't likely to kill your entire crew or destroy the only space gas station for tens of millions of miles. The Sahara is inhospitable and will kill you if unprepared. Space is downright hostile.

You can't really be taken seriously when you sort of hand wave the challenges doing anything in space. It just sounds like you're pointing to some sci-fi books as if those are the answer to everything. Space is hostile and doing anything in it is dangerous and expensive. Any resources that exist there are orders of magnitude more difficult to access let alone exploit than any on Earth.