Marketcap is an extremely flawed way to look at things.
Having a giant supply of coins is an easy way to manipulate the flawed coinmarketcap. Let's say I create a coin and have 200 million coins outstanding. I sell one coin for $100. Now I have a $20 billion market cap. That doesn't mean I have a market for my 200 million coins. There may only be one person in the world willing to pay $100 for my coin. (my mom and she doesn't have $20 billion to buy the rest of my coins)
Bad example. You don't need to sell whole coin. I can sell 0.01BTC at 12k. You don't need 12k USD to register a trade and change the price of BTC for a moment.
I can make a blockchain even with one coin or contract with 1 token and 16 decimals. Then I can sell 10(-16) amount of that coin at 10(16)USD price. And market cap value of that coin will become 10(16)=10000000000000000 USD. How much money I have invested? Only 1 dollar.