Yes, it is speculative and subjective - but so is all value. You can't factor that out, because it is inherent to every transaction that humans ever make. We make decisions based on our own valuations of expected future outcomes.

Even the value of the bridge is not realized until people cross it. It takes decades for such investments to break even, if they ever do - far longer than a GPU (which probably costs less than a mere boardwalk across a ditch).

Accountants are doing exactly what they should - every asset and liability is broken down by its market value (speculative) which investors then use to inform their speculation about the value of the company. If they think the company is more valuable than the current market price, they buy more stock. If you think the market value of a GPU is too high, don't buy it.

The market can be (and frequently is) wrong - but it's not an accountant's job to predict that.