How do people save up a downpayment from $0?!

How do people save up $80k-$100k+ for a downpayment (starting from $0)?! What are we missing? For us to do this, it could take 15+ years. On top of saving for retirement, car replacement, rent increases etc.

I understand there are loan options to put 3-5% down, but you still have to pay closing costs AND be able to make the monthly payment.

EDIT: I know FHA, USDA, etc. are options but you still have to be able to afford the payment every month.