The answer is yes. You can own a fraction of bitcoin and it doesn't matter how much it is. If we see a worldwide adoption of Bitcoin, people from all over the world will be using Bitcoin. 21 million bitcoin is not enough for 7 billion people if you count it by the numbers. But that's not the case here is it? 1 Bitcoin is not a single unit. You can divide it into small fractions and distribute them to different people.

Bitcoin mining will be over one day. Maybe then we can see stability in the market. Even if whales hodl Bitcoin to that point in time, they will have to use it to make transactions. The circulation will continue and everyone will have access to Bitcoin for sure. But that's in the far future. no one knows what will happen.