I think sometimes that some of these people start out for real in their faith. The power of money is the great seductive force that many have fail to including men and women of God. I don't know if she was but I have seen people change to the dark side.
Yup.
However, probably more powerful and damaging is the pride factor. It is very easy to delude yourself into believing that you are something great and powerful.
I had a very close friend who about 10 years ago was asked to take over and lead a ministry with a LOT of support. This was by no direct action of his own, and they had to work hard to convince him. Two years of it changed him completely, only after it all came tumbling down and a few years of self reflection did he begin to resemble the humble servant type that I knew before.
It is so easy for someone to start something good, then it turn into "<insert name> Ministries". It is also very easy to get caught up in it. IMO The real ones (and ultimately most effective) are those that work as part of something greater and do everything they can to stay out of the limelight. There are thousands of them to the one that gets the attention.