What am I doing wrong with this analysis?

[Matthew Terry]

I'm taking initiative to analyze deals on a consistent basis for practice and to uncover potential opportunities. I recently saw a multi-family property, 16 units B class in a decent area for $2.4M on Loopnet. Seller will only do seller financing, 30% down and 5% IR 30yr. The claimed NOI is $129,500, 5.4% CAP rate. Debt service would be around $108,000 on a $1.68M loan, which leaves $21K. That is about 2.9% return on the $720K down payment. I don't know if property management was part of the NOI calc. Assuming it is and assuming you wouldn't have to spend another penny on repairs or improvements, why would anyone use $720K for a 2.9% return and all the potential hassle and risk of running a 16 unit building? I made 7% on Fundrise this year. Selling cash to a hard money lender would get 4-5% easily. LP in syndication would generate double that. Even a dividend stock portfolio would easily return more. All these examples are completely passive. Is there just massive speculation in the Phoenix multifamily market now? Am I not considering something? Do sellers price their properties high on Loopnet for an anchor when the buyer negotiates down?

For reference: 
https://www.loopnet.com/Listing/643-E-Brown-Rd-Mesa-AZ/17255707/