That’s a good question, because it sounds as though the Vatican, being the headquarters of the Catholic Church, is being hypocritical in not following what the Bible says.  We need to be careful, however, in understanding the whole Bible’s teaching on wealth.  The two incidents you have picked make it sound like Christians aren’t allowed any possessions at all.  These are two isolated incidents, however, which don’t reflect the whole of the Bible’s teaching on the subject. 

When Jesus calls people to follow him, it is to follow him with all of our lives, including all of our money.  In the first incident (Luke 18:18-23), the man’s wealth was stopping him from following Jesus.  For this particular man, Jesus told him to give away all that he owned.  In the end, he chose not to follow Jesus and went away sad.  He was not willing to give up his possessions.  To give up all his wealth was a specific command to this one person and is not a general command for everyone when they become a Christian.  In fact, in the very next chapter we see another story of a rich man who wasn’t asked to give up his possessions (Luke 19:1-10).  Instead he freely offered to give away half of his possessions. 

Possibly the clearest biblical teaching on what Christians should do with wealth is found in 1 Timothy 6.  In that chapter it tells Christians that they should learn contentment and that they should not be greedy (“The love of money is a root of all kinds of evil” - 1 Timothy 6:10), but it also says that Christians who are rich should do good and be generous and ready to share.  It’s not wrong for Christians to have lots of money, so long as they are being generous and are putting their hope in God, not in money (1 Timothy 6:17-19). 

I don’t know how the Vatican got so much money or what it uses it for, so I can’t really comment on that. But Christians follow what the Bible teaches, not the Vatican or the Pope.  To learn more about Catholicism and Christianity, check out:

http://www.christianity.net.au/questions/catholicism_and_christianity