drop a mouse into a pool full of pyranhas and see what happens
build those section 80 houses in that hood, go ahead...do it.
The problem arises when not only one mouse is dropped, but a million at once, many of the mice will struggle and emerge victorious, possibly even favored by evolution or just blind luck.
Many Many more of the mice will be ripped apart by the pyranhas, never even getting a glimpse of life beyond that miserable pond.
The pyranhas will keep consuming.