How does their house benefit us, the average hard-working people? Not.
Kingdoms were of use in the past, where the kings/queens made all decisions. But nowadays they're entirely useless (in most countries) and more of a symbol.
Symbols or figureheads like them directly have an impact often on those that live in the society that they share.
While they may not have obligatory administrative duties, they can and have used the influence they wield for the good. Many modern day royals are behind charities, hospitals and educational projects.
In fact, these princes' southern counterparts were responsible for the first colleges for young women, who in the past had few opportunities.
It is easy enough putting royalty and money in the same basket; a bit like today how we tag the so called 'bankers' and business leaders with the fat cheques. It may be true for some, and they may live that lifestyle (which is not wrong at all; people just like to look at the extremes of things and then talk about it loads), but it is not the case with the vast majority. It is the minority, even in that branch of work/'class' that are incredibly wealthy.
I am quite fond of the
Travancore Royal Family. Despite being one of the most affluent houses in the world, given their assets and various sources of funding, they are some of the most humble people. Their kings have a particular tradition of paying respects to a special temple (was on the BBC and other media outlets in last couple of years) on a daily basis. If, for whatever reason, they fail in this task they have to give some contribution to the temple's funds. Historically, these funds were kept secret and used specifically in the case of great calamities as a safeholding, from which money can be used to feed and look after people. Today, this amassment of donations and general wealth is supposedly valued at prices up to $20 billion, none of which is being misused.
Such people unify society and make up in the areas where day-to-day governments, vying for votes, fall down. Not unlike religion, it gives people a meaningful symbol and their ability to stay above the political fray is something to be admired. The current King of Thailand, though part of a constitutional monarchy-government system, has been the one figure in recent weeks to unite the nation and give rest to the protests that have been taking place.