It's better to have a terrible 5-6 years dealing with diapers and strollers in your 30s than spend 30 years in your 50s to 80s alone.
It is totally normal to expect children to care for you in your old age. The guarantee is that other people can and should ostracize people for not caring for their parents. When an acquaintance tells me they don't visit/call/care for their parents with pride, I make a mental note to not be friends with that person. If you can't keep the most basic relationships straight... that's not a great sign, realistically.
After that period things are great!
. . . until you've faced with a household full of teenagers rebelling against anything and everything in overly dramatic ways.