The Mormon Church is much wealthier than Watchtower for a number of reasons.
1.They tithe their members. This means that to be in good standing, or to get a temple recommend, you must provide evidence of giving a tenth of your income to the church.
2. Mormons value education, professional careers, and celebrate success, and are thus much wealthier than JWs.
3. Watchtower got complacent because they had a steady source of income from book and magazine publishing until the 1990s. When that income dried up they had to fall back on donations, but since JWs are not as wealthy as Mormons, and not in the habit of contributing significant amounts to their church (apart from for the literature) donations are at a much lower level.
4. Mormons are more business savvy because they don’t eschew politics or big business the way JWs do. Many prominent Mormons are also businessmen and politicians themselves, and know how to play the system and are in a different league from JWs when it comes to investing their capital.
You can see this in Britain for example, where there are fewer active Mormons than JWs, yet contributions to their main charity is higher than for Watchtower and the IBSA in Britain. In the US the disparity between the two is bound to much greater, because there are more Mormons, and the gap in wealth between the memberships of the two groups is likely to be greater.
Watchtower may have made $2 or 3 billion from the sale of property over the past few years, but they have annual running costs somewhere in the region $1 and 2 billion. I doubt they have much money in cash or investments at all, apart from the property they still hold.
