I heard a well-known quote about stock market that the market is not far from crash if even taxi drivers are talking about stock investing.

If you look at the stock market, do you wait for it to crash before you buy?

A truly diverse portfolio of RE, precious metals, stocks, bonds, ect ect, will have 'average' results in relation to the economy. 

But having a few trusted investment partners if/when you need them is a great backup plan if a deal pops up that you can’t take on alone.Return on investment thesis:To do this deal effectively you need to know How much money goes into the deal, How long the money stays in the deal, How much money comes out of the deal and What is your targeted internal rate of return You can also compare how buying this property compares to buying a different property as well as the opportunity cost associated with alternately investing in stocks, bonds or a business.

Is it better than the stock market?  

I keep a certain amount in cash for emergencies whether personal or business related and business operating income, and the rest goes in the stock market, or stock like assets.

It helps you compare how investing in one property will compare vs investing your money in another property, or the stock market, a CD at your bank.

Property ownership (from within the SDIRA) takes on certain limitations with the responsibilities that you don't want the IRA to take.With a loan, it's just paper...just like an investment in a stock or bond.  

Not traded on the stock market.

The funds trade like stocks, so the risk of losing value is there.