I'm not sure about ethereum,
Ethereum so far still has a good volume and value, so it's not scam yet.
but bitcoin now definitely has some value. But at the same time it can fall to almost zero, so it is a very risky asset.
Bitcoin represent the crypto world since it's the most popular and the most dominant coin in the market.
This crypto world could still live if other coins like ETH will result to scam but if BTC will become a scam, everything will die, and we all loss money.