Untrue. You can actually mine the Venusian surface for metals. Carbon, hydrogen, oxygen, and nitrogen (the vast majority of the elements used by life) can be extracted from the atmosphere, as well as sulfur. So from an elemental standpoint, it actually could be self-sufficient. Not that you’d WANT to avoid trade with other planets, but it is possible.
It is also possible to terraform Venus, although much more difficult than for Mars.
It is also possible to terraform Venus, although much more difficult than for Mars.