You might not get another job at the same level. your career might never restart.
Also people plan around one kids. But when there's more than one then all these plans extend, as do costs etc.
Its not about Disneyland. Its may be about never having any holiday, kids extra activities all cost money.
Drop a 2nd car, can affect what activities you can do on the same day. When you have 2+ kids doing say football 3 times a week, the time just disappears.
Then again, many have no option. You might have 3 kids in primary school. Someone has to look after them during the summer.
Also as the kids flee the next, or become independent, then looking after parents becomes an issue. if you think kids are expense don't look at nursing care.