This ignores everything about supply/demand and market bubbles.

Not at all. Bubbles are only obvious in hindsight. If somehow you are prescient enough to recognize them reliably in advance, you can make yourself a cool billion easy.

This still ignores that speculation can contribute to them, and can move the market. It's is not a rebuttal or an explanationa.

If speculators realize there's a bubble, they'll short it and thereby make money when it collapses.

Shorting a bubble moderates its price rise.

And if they don't realise there's a bubble, but continue to add 'buy' side pressure?

Speculators are part of the market, not observers, and they absolutely contribute to rising prices, not just price discovery, because they add demand.

> they absolutely contribute to rising prices ... because they add demand

Speculators buy and sell, in equal measure. That's what makes them speculators. It's a net zero.

If they bought and held, they'd be investors.

Helping to push up prices as they do so, attracting more speculators. That's not a net zero.

They also hold what are limited resources for a non-zero amount of time, reducing supply in aggregate. More speculators, more supply constraint.

This is not some sort of idealised marketplace where people can dip in and out without any effect.

You're missing that they short things they believe are overvalued, like in bubbles.

> This is not some sort of idealised marketplace where people can dip in and out without any effect.

You're right. Speculators work to decrease the peak of a bubble and increase the value of a dip.

The misapprehension is thinking the effect is only one way.

> You're missing that they short things they believe are overvalued

In the housing market? LOL.

> Speculators work to decrease the peak of a bubble and increase the value of a dip.

Except that's nonsense, they increase the demand on an already massively in-demand resource, accelerating price rises.

Your ideas fly in the face of observable reality.