As the question interested me, I thought I would see what I could find. The first search hit naturally was to unsubstantiated accusations, so I changed the search and came across this link
dici.org/en/news/vatican-accounts-show-a-positive-balance/ which says that after years of being in the red, the Vatican managed to go into the black. The next find was the Vatican’s bank’s annual report
ior.va/Portals/0/Content/Media/Documents/AnnualReports/425x00sc399T!/IOR_AnnualReport_E.pdf.
The money belongs not only to the Vatican State, the Holy See but also to all those Religious Orders who are raising funds for the poor and need to collect it from all over the world and then get it changed into a local currency and available in some remote location. The Vatican also employs lay people so it has to pay staff wages and pensions.
The Vatican does own millions in artwork but considers itself custodians and apparently doesn’t charge non Catholics to see it. For some strange reason, some outsiders think that the Vatican personally owns the real estate of every Catholic church, school or hospital.
I wonder whether the OP’s Dad realises that Western politicians make many trips to the Vatican as guests, but do not welcome a return visit, or that when they do, the Vatican contributes to the visit. I was fed up at the whines in the press about the cost of the Pope’s visit to the UK especially as they glossed over the cost to the Vatican of visits by our members of Royalty and numerous politicians over many years, and the fact that us Catholics paid for all the non-state parts of his visit.
Funny how I could not find an account of the wealth held by other churches or faiths, however, in fairness to them, I probably didn’t know where to look. Also, the Catholic Church is unique in that the Vatican is not just the place where the Pope lives but is also a State in its own right, so it is not comparing like with like.
Maybe your Dad would be interested to know that in some parts of the world where Catholics are very much in the minority and some of the least wealthy, they give more to help others than many other churches or religions. I intend no disrespect to other churches or faiths, we all have people who are not blessed with the gift of giving and others who are blessed abundantly in giving of time, talents and where able, money.
Thanks for the question.