Is Bitcoin's value predominantly driven by speculative psychology?

This is an excellent question, and it really hits the nail on the head. It's undeniable that speculative psychology is the primary driver behind Bitcoin's dramatic price fluctuations.

Just look at its price curve – up 20% today, down 30% tomorrow, like a roller coaster. Most of this is due to the forces of "hype" and "speculation" at play. Many people buy Bitcoin not because they genuinely want to use it for purchases, nor because they deeply understand its technology. They simply believe it will rise in value and want to "buy low, sell high" to make a quick buck. Once this sentiment creates a herd effect, it can push prices sky-high or send them plummeting. From this perspective, saying it's speculation-driven is absolutely correct.

However, to say that Bitcoin's value solely comes from speculation might be a bit one-sided.

While speculation amplifies its price volatility, there are underlying factors that support it, making some people willing to hold it long-term rather than just engaging in short-term trading. You can think of these as the "foundation" of its value. If the foundation isn't solid, even the tallest building will eventually collapse.

This "foundation" primarily consists of the following points:

Scarcity (Rarity makes it valuable): This is the easiest point to understand. Bitcoin's total supply is hardcoded at 21 million, not a single one more can be created. Just like limited-edition sports cars or famous paintings, when something is scarce and many people want it, its value naturally increases. Why is gold valuable? To a large extent, it's because its reserves on Earth are limited.
Decentralization (No one can control it): This is its most core characteristic. Money you deposit in a bank can be frozen by the bank, and governments can devalue your currency by printing more. But Bitcoin is different; it doesn't belong to any country, bank, or company. As long as you have your private key, your Bitcoin truly belongs to you, and no one can arbitrarily take it or freeze it. This "I control my own assets" feature is very attractive to people in economically unstable regions or those who distrust centralized institutions.
Store of Value ('Digital Gold'): Based on the two points above, many people view it as 'digital gold.' When economic crises occur in the real world, or when excessive money printing leads to inflation (meaning money becomes less valuable), some people choose to convert a portion of their assets into Bitcoin to preserve value, just as people used to buy gold. It's also much more convenient to carry and transfer than physical gold.
A Global Payment Network: While using Bitcoin to buy coffee isn't practical right now (it's slow and expensive), it holds value as a global transfer system. You can send money from one end of the Earth to the other, much like sending an email, without needing any banks in between. Especially for large cross-border payments, it can potentially be faster and cheaper.

Let's use an analogy:

You can imagine Bitcoin as a world-famous painting, like the Mona Lisa.

The "foundational" value of this painting lies in: it was painted by Leonardo da Vinci (a unique creator), there's only one in existence (scarcity), and its artistic value is universally recognized (consensus).
However, the exorbitant price it fetches at auction, perhaps hundreds of millions, is heavily influenced by "speculation." Many people buy it not just for appreciation, but because they believe it will be worth even more in the future. Market enthusiasm and buyer sentiment can lead to dramatic price fluctuations.

So, returning to your question:

In the short term, the vast majority of Bitcoin's significant price fluctuations are driven by speculative sentiment. Market euphoria and panic cause its price to swing wildly.

However, in the long term, what has supported its journey from zero to its current value is the underlying consensus regarding its scarcity, decentralization, and status as 'digital gold.'

One could say that speculators are the waves on the surface, while the underlying consensus is the undercurrent that determines the direction. Without this undercurrent, the waves wouldn't be able to form.