Remember you don't have to own a property to control it.

Do you just buy all cash, say 2-4 houses, or do you leverage with mortgage debt and try to expand the assets you will control?  

In many cases, the child will have the ability to own and control legal title title upon reaching majority at age 18.

The alternative is that if someone gets hurt working for you in an environment you can control and they cannot, you will be liable in tort.

It seems from reading and my knowledge of intangible assets the benefits are many for them, such as depreciation offset, saving on commissions, stretching out the capital gain, earning a better return than the bank, a degree of control, etc.

Increase retention (meaning up your deductible), but also look at things like putting on hail proof roofing, etc, or go uninsured and maybe increase loss control as well. 

How much does not being able to control the other two hurt the value of the ones on the right? 

It's not just about the commission, but about the control you have over the deal.  

As mentioned above those who are holding large inventory plus the hedge funds are slowly releasing their inventory in a controlled manner to maximize gains  to prevent a price collapse As interest rates rise prices will come down but it is a more normalized market then 2007-08

After your friend has done some emergency "damage control" and he's got the dryers/fans going, he will want to call his agent.