You'll also need a solid property manager who can rent the property out quickly once it's ready to go so you can get some tenants in there and maximize the value. 

Not having the right management can kill a deal (I'm looking at sponsors that self manage)And understanding the debt structure.

Out of the eight units I own and manage, I have had countless tenants choose our properties due to in-unit washer/dryer.

I didn't have the time to fix and flip, or buy one single family home per year, and try to manage it.Two big differences between SFH and Multifamily.

It's important to take your time with tenant screening and be prepared to manage the property yourself.

It's possible the deceased father agreed to let her manage the property and keep the rent net for her troubles, but the title/ownership remains in him so his heirs would inherit it as a legacy.I suggest your friend familiarize himself with the statute of frauds which I believe requires agreements regarding real estate be in writing to be enforceable.

For 15 years you manage to save up $20k per year and you have the missing $300k to pay $400k in cash.

I thought it was incredibly hypocritical when I worked for a bank and got those requests from "risk management".

In choppy markets, being a hard money lender allows you to capitalize on opportunities without directly owning and managing properties.

You didn't even mention tenants who don't pay rent, evictions, vacancies, HOA violations, the consistent rise in taxes and insurance, bad property managers, and the many other issues that cut into your profit.