[breischl]

Speculation actually does deliver value. Whoever sold to the speculator gained value - they got rid of some risk, and gained enough cash to make it worthwhile. The speculator might also deliver value to whoever they sell to, particularly if the speculator lost money on the deal. Plus they provided liquidity, which sounds like BS until you need that liquidity (eg, try selling a house in a slow market)

Banks deliver value too, unless you prefer to do all your transactions in cash that you pull from under your bed and you never need a loan for anything.

Rent-seeking is indefensible pretty much by definition, although I think people tend to perceive many things to be rent-seeking that actually aren't.