I legit went from "hmm I disagree, but understand where he's coming from" to "this guy is deluded and crazy".
Property prices are super high everywhere right now and it's easy to understand how some people want to live rent free whilst earning so they can enjoy extravagant lifestyles.
But at 40, they're pushing it too far, to force their 70+ y.o. mother to carry them while they offer nothing in return.
IMO letting them chill for 40 years rent free is more than enough payment for 'being born'. If they weren't earning or were disabled etc and needed care etc then it would've been fine, but they're legit deadbeat freeloaders who won't bat an eyelid if their mom died.
If they haven't got a place to live, tough. They'll learn the hard way. 40 years is plenty of time to have figured it out.