Unscalable

1903, W. E. B. Du Bois, The Souls of Black Folk, I. Of Our Spiritual Strivings, Why did God make me an outcast and a stranger in mine own house? The shades of the prison-house closed round about us all: walls strait and stubborn to the whitest, but relentlessly narrow, tall, and unscalable to sons of night who must plod darkly on in resignation, or beat unavailing palms against the stone, or steadily, half hopelessly, watch the streak of blue above.

[…] Remember, sir, my liege, The kings your ancestors, together with The natural bravery of your isle, which stands As Neptune’s park, ribbed and paled in With rocks unscalable and roaring waters, With sands that will not bear your enemies' boats, But suck them up to the topmast. […]

The other end of their promenade was closed by a lofty and almost unscaleable precipice,the abode of hundreds of sea-fowl of different kinds […]

The idea has its detractors. Skeptics argue the whole idea is unscalable, and that large vertical farms would be insatiable consumers of energy to keep the plants lit, healthy, and harvested […]

The result is a marketplace where low-revenue companies (say zero to $2 million per annum) are attracting valuations in the tens of millions of dollars and raising too much money. Most of these businesses will turn out to be poorly run, not special, unscalable, and will not deliver negative returns.