1) The more well-employed people are around, the larger the tax base.
2) The larger the tax base, the more likely we operate with a surplus.
3) With a surplus, business can make reasonable bets on future productivity and hire even more people, further increasing the tax base.
Done right, the theory of paying help well and sticking with them leads to a stable situation with low crime, clean neighborhoods, and a populace with pride in itself. A place the rich can be proud to live in.
Throwing away people is just utterly destructive of a cohesive society.