One thing to understand about the LDS church is that the leadership is drawn from the membership, but is really really not representative of that membership. In order to become a member of the Quorum of the Twelve Apostles, the highest leadership body in the church, you essentially have to have spent decades serving full-time as a church leader at lower levels. This means that all the members of the quorum are old men (and yes, they are all men - that's another discussion). We have been accused - correctly - of being a gerontocracy.
There are two implications of this. One is that on social issues, the church leadership lags the membership by at least a generation, usually two. Furthermore, the upper membership of the church leads by consensus, ideally unanimous consensus. It takes a long time to get more than a dozen people on the same page about almost anything, much less something like the theological implications of homosexuality (to name one topic of the day). This goes some way to explaining why the leadership keeps getting caught flat-footed when regarding issues of transparency, LGBTQ relations, race, and so on. They aren't the internet generation and it shows.
But it has a second implication as well. Church leadership often remembers and understands church history completely differently than the lay membership does. In particular, for this issue, in the early part of the 20th century the church nearly went bankrupt. They ended up calling several people with strong business backgrounds to the Quorum of the Twelve, and one of those went on to become President. They managed to put the church's finances on a firm foundation. For obvious reasons, none of this tends to get discussed in Sunday School, and most of the membership of the church no longer remembers it. But the leadership most certainly does. In addition, it led to more and more church leaders having business backgrounds instead of pastoral care backgrounds, and as a consequence they tend to view achieving a good ROI on "the Lord's money" as being a primary good. I personally disagree, but it is what it is.
Next, one thing to note is that none of the church leadership is personally getting rich off of tithing funds. The leadership draws a salary; that salary lets them live comfortably, but it isn't 7 figures. Nobody lives in a mansion or flies a private jet. So, then, why are they sitting on an enormous cash pile? In my personal opinion, it isn't primarily about the money. It's primarily about increasing commitment to the institution. Paying tithing is "faith promoting". It gives the membership skin in the game. They aren't just showing up to a church building for two hours on Sunday. They're actively participating in building the Kingdom of God.
Of course, you can take the phrase "commitment to the institution" two different ways, depending on your going-in assumptions. For the faithful, building the faith of the membership is a primary good and indeed a principal goal of God. For the skeptical it looks like brainwashing with a nice side benefit of extra cash in the coffers.
The next obvious question is, even if you're one of the faithful, and you assume that paying tithing is indeed a good way of building a faith community, can't they come up with ways of using the money that are more in line with Christ's teachings than buying up 2% of Florida? And I wholeheartedly agree. There are. And, of course, owning large tracts of real estate and a mall in downtown Salt Lake City and your own private securities investment firm don't make a lot of sense if nobody in the leadership is living like a sheik. So why not spend all of (or at least a lot more of) that cash on charitable works? Why not just go in and rebuild Haiti, or cure cancer, or something?
And I honestly don't know. I go back to the leadership's business background and their recollection of the church nearly going bankrupt, and I can sort of see it... but then I read the Sermon on the Mount, and I can't again. I have to chalk it up to a lack of imagination, combined with a loss of pastoral care instincts in the church leadership.
For what it's worth, I think it will change... eventually. The time constant of change in the LDS church is something like 20 years, so don't expect it to happen tomorrow.
Finally, for those of you who have left the church and felt like it tried to take your dignity when you left, I'm sorry. My wife left, and that wasn't our experience. Your experience with the church is almost completely due to the culture and local leadership in your local congregation, and in a lot of cases that can be quite good, but it can also be fairly toxic if you're unlucky. I've experienced both, but more of the former. Of course, my experiences don't help you if yours are different. I hope you find your peace.