But if a coin is rising slowly, doesn't invest millions in marketing, it still can be a scam. And if it's not a scam, it's probably just a shitcoin that won't create anything valuable.

Crypto space doesn't have good investment opportunities. It doesn't create something that is actually used by people, and as the result creates value for investors. It only has speculation opportunities - you buy low and the price increases because other people bought after you. Eventually the price crashes and those who bought the latest suffer a loss.