For them it is probably safer than the stock market and they can use 'cash' or Self Directed Retirement funds.

It's not like stocks, where an Enron can go to zero.But if/when we have a correction, I'll probably use it as an opportunity to buy more properties.

Also, as mentioned above, completely stocking a house from scratch is a lot more expensive than you may think as everything adds up and up and up; so make sure you are budgeting your investment cost with that in mind. 

I expect my rental income to cover mortgage payments of course, but I can also cover things as needed by pulling out or borrowing against my stock investments - so losing my active income source isn't a huge concern for me.

Warren Buffett became the wealthiest stock holder in the country by following These strategies

Could be via stocks recently sold or an asset.

AEG is a private company though  so can't even buy the stock in it.

So, since it would appear that I am going to have to take a pay cut regardless of what I do, I figured it's time to look into a career change.I want to get into RE as I think it ties well with my analytical nature and I have an interest in building wealth above and beyond stock market returns. 

Assets: This will be liquid assets such as checking/savings, 401k, IRA’s, stocks, etc.

I now know the basics of investing in real estate and how to be a good well rounded agent (the only thing I have invested in is stocks and crypto currency so far).