“The Holy See gets by on a very tight budget, if you care to know the truth.”
You can have a tight budget and still have immense wealth. The two things are not necessarily related. If you want to convince people that the Vatican is poor, you’ll need to do a lot better than that. They own 15% of the stocks on just the Italian stock market alone.
The Borsa Italiana has a market capitalization of over $1 trillion. You are asking readers to believe (with no evidence) that the Holy See has liquid assets of over $150 billion? If you think they could be sitting on that kind of wealth and not be spending it (or even the dividends and interest earned), you don’t know human nature.