Ok, a more charitative reading of the parent: it is (badly) referring to the idea that public services are not a bad idea just because they operate at a loss, due to their positive externalities. E.g. a road is a “bad investment” if you only look at direct profit (which is 0 if you dont set up a toll).

Obviously they do provide value and that value can often be defined as indirect monetary return. There’s also value for the country that is not easy to monetize in money terms, such as more education helping voters be less manipulable.

Education or healthcare provide returns which are not directly monetary.

My father was on sick leave for six months waiting for surgery. When he finally reached the start of the queue and got the operation he was back at work the week after, again becoming a taxpayer. Of course it pays to have working healthcare. And it even pays more to have a healthcare system which gets more people back to work as quick as possible. That's so short from "directly monetary" that I don't see the difference.

They provide a monetary return.

Could you prove this? Specially education. It seems to me that educated communities bring investments of sectors that need some specific skills.