Okay, they have some real estate holdings. But they've also provided significant relief for every major disaster in the past century. In addition, they offer job search assistance, food assistance, etc., through a network of farms, canneries and thrift stores. And all of this is funded by member donations in addition to the 10% mentioned by the GP.
But none of that's the point. The GP was pointing out that a not insignificant portion of the population donates more than 10% of their income on a regular basis. In light of that, 5% isn't much, particularly for someone with a great deal of income.
My point is that a person donating 10% to an inefficient charity like the Mormon Church is not as laudable as, e.g., a person donating some fraction of 10% to one of these: http://www.givewell.org/charities/top-charities
But none of that's the point. The GP was pointing out that a not insignificant portion of the population donates more than 10% of their income on a regular basis. In light of that, 5% isn't much, particularly for someone with a great deal of income.