That’s 7% annually
Nothing crazy
It's more complicated than that.
You gotta think of Housing more like a dividend paying stock or coupon paying bond, which have an upfront value, plus a yearly distribution ,plus an artificial tax depreciation. In that context, it's a great return that more than doubled the same return if the money were invested in a s&p 500 index fund.
Those women made nearly double that 7% in the early years from rent and nearly 2.5 times that return from rent later on. In their newer years, apartment buildings regularly give 6-8% yields and easily give 12-15% yields once they get old simply from rental income. This doesn't count generous tax depreciation in the first few years of ownership.
It was a great investment when considered holistically. Consider the fact that the avg stock barely gives you 2% in dividends, which can be arbitrarily suspended by the board, unlike rent which is constant over that time.