Bitcoin is limited in quantity. News like so and so billionaire or so and so company bought 100,000 BTCs is now commonplace due to the dip. Will there be a time when there will be no bitcoin to buy. If so then what will happen then?
No, because if someone buys all the bitcoin, then no one will ever want it. It's like if someone buys all the USD, then what will happen? One man will own all the USD but the whole society will implement new currency.
Bitcoin isn't a first need thing like food and water, so there will be zero demand on it in that case. If someone owns all the water and all the food, then sure, people will fire everything to don't die in starvation. I think this is the simple explanation of that situation.
Plus, if crypto is the only concern here, remember that we have Ether, Monero, bitcoin clones (Bitcoin Cash, litecoin is also clone, etc).