"All that money", hah, they have four kids. It will evaporate into the scream-filled ether faster than they can remember the password to their online banking.
You get a shower for your first baby and you can easily get enough at that one shower to provide a basis for four kids.
Sure you need to buy some new things with each child but most of it can be handed down. That's why you don't need a whole fund. You can use things over again.
Plus the medical expenses for four children would be mind-boggling--best case scenario each child will still have far more complications than a singleton. It's almost unheard of to have more than two and have a vaginal birth.
I think most parents of singletons are deeply sympathetic for people with multiples. Twins are less extreme but still healthy twins are exponentially harder than a healthy singleton.