There is a difference between overbought assets and scams, and it usually goes along the line of, the easier it is for a small group of people to walk away with all the winnings the more likely we are to call it a scam.

Cryptoassets are a suitable vehicle for scams just as bits of paper with holograms on it or devices with touch screens can be - all it takes is a suspension of disbelief and caution which we also see with overbought assets. And there's a fair share of altcoins and ICOs that look quite scammy to educated people, while BTC/ETH/LTC and some others have survived a decade of people trying to poke holes into them.