Anyone can create a token named 'Bitcoin' on a blockchain like Ethereum or BNB using smart contracts. But that's a different kind of scam. But the fake Bitcoin that I want to talk about, is actually created by some exchanges themselves!
Let me tell you. Bitcoin has a limited supply - only 21 million. Moreover, with the rise in popularity of BTC and the fear of hacking on various exchanges, more people than ever have started keeping Bitcoins in their wallets. As a result, the amount of BTC deposited in the exchanges is decreasing every day. Everyone knows that BTC is the most popular trading pair with any other crypto. But if the exchange doesn't have bitcoins, their business will go downhill.
That's why some exchanges have created their own coins with the same value as real Bitcoins by placing stablecoin collateral with bitcoin equivalents! Since exchanges do not immediately add crypto trading on their platforms to the blockchain, this leverage is difficult or almost impossible to capture. Because, common users don't understand anything.
But what is there to worry if the daily activities of the users are not disrupted? Of course there is. Exchanges that make fake bitcoins are really weak exchanges! And, trading in such an exchange is very risky! Therefore, it is better to do most of the transactions on the top exchanges according to the exchange rating on the Coinmarketcap site!
We can't actually label them as fake bitcoin because exchanges never pretend those tokens as real BTC but knowing the fact bitcoin has the most popularity and no trader can't avoid using it then they go for such moves of creating their own tokens with same value as Bitcoin but I don't think any exchange enforced their users to convert the Bitcoin to the pseudo bitcoin tokens.