Yes, companies can legitimately lose their value over time. Think of Kodak or Nokia - would you say they are producing as much value as they were in the 90s or 00s?

Now, some stocks have a real value + speculative value on top. Netflix and many other tech companies are in this state, and the speculative value can go down way more than the real value. But the floor for Netflix stock is waaaaaaay above 0. The floor for BTC and similar is 0, by contrast.

As for pump-and-dumps and insider trading etc - sure, they happen, just as thefts and muggings happen. But they happen a lot less then in crypto-land where they are fully legal, and where, even if they weren't legal, no one would be checking for them.