He repented of his position on Jews.
How did he make his 25 million? Based on earlier profiles it seems to indicate he took a very modest salary on the preaching thing. I'm ok if you are a preacher and you write a book and that book makes you rich. Just don't take a massive salary from your congregation, ask your congregation to provide you with a private jet, or tell your congregation that you are wealthy simply because God favors you more or you have more faith.
He wrote 33 books and ran a multi million dollar non profit.
http://time.com/money/5168865/billy-graham-net-worth-quotes-money-greed/
While the link can't provide exactly a basis for how he earned his money, given the evidence it presents it sounds like the majority of that came from selling books. The biggest thing that stands out is in 2005 he was earning 450k a year for running his non profit. But I would submit to you that a lot of people who are in charge of non profits of that size earn a lot more.
I don't see a lot of issue in his wealth there.