First, a lot of people exploit old people (some registered nurses, members of heavily regulated profession, with multiple degrees and licenses in nursing and medical sciences come to mind.

It varies tremendously depending on what state you're in, home value, whether it's owner-occupied full-time, etc.   

That will vary for each person. 

We have an experienced, degreed designer on the team and we have "trade accounts" with vendors, so we'll often purchase the materials and appliances directly from the vendors and have the contractor pick them up to use on the job.

Politics definitely effects taxes and the economy.I'm sure relevance will vary by location, individual, type of investing activity and other factors.

For the past few years, there has been consistent and rapid growth in the Jacksonville area.When it comes to Class B, C, and D neighborhoods, it's important to note that classifications can vary, and it's not always solely based on zip codes.

The guidelines for ADUs will vary from lender to lender, but there are options for those, yes.  

The tenant’s contribution to owner will vary as their income shifts.  

The shape of the properties varies.

But if “by doing” he means investing without first having the knowledge to KNOW the risks, EVALUATE the risks (and potential rewards) and to TAKE ACTION to reduce the risks then the cost of this learn by doing education is probably going to be significantly more expensive than a degree in real estate from MIT, let alone reading the\ree or four texts on your own.