something I can't really understand...

Since CPs claim that it costs SO MUCH MORE money to have an additional
child in the home...meals, electricity, insurance, mortgage, etc...How
do they make ends meet once the child support is over, at let's say
18? Do they all of a sudden go hungry or does the CP lose their house
since they can no longer afford the house payment for the additional
child/adult, do they lose their car or insurance since they can no
longer pay the original amount? Or maybe the electric company, the
mortgage company, etc...now lower their bills so they can manage???
Or do they just kick out the 18 year old as soon as the last check
comes in? Or do they make that 18 year old get a job and pay the
equivalent of what the non-custodial parent paid in CS, so that they
all still have a roof over their head, electricity, etc???

I'm just wondering since they all claim that the cost of child support
is NEVER enough to cover the additional cost of raising a child...then
you would think they lose their house, get their electricity shut down
or kick out their kid and all of a sudden, their bills are reduced by
1K (or whatever the CS amount is) so they can continue their lives?