Depending on the property and the deal, an experienced investor may want more than a 30% spread (and in some deals, they may be willing to take less than a 30% spread--for instance, if the property will produce incredible cashflow after rehab, they may accept a lower spread). 

For instance, in a scenario where several properties in an area are sold at a discount due to defaults, these sales set a new standard for cap rates in that area.

For instance, I once asked a family friend to loan me some money for an investment property.

However in many instances, the total return on investment within a syndication will not be as high as a well managed property that is purchased at the correct price.

Good article from NAR on advantages of listing with an agent versus FSBO https://www.nar.realtor/magazine/real-estate-news/sales-mark...

In 12 years that I managed my own rentals in ON there had been a few instances where I had to deal with problematic tenants and each time we resolved our issues without involving LTB.

For instance, someone might find a 100k spread on a deal like this perfectly comfortable.

Getting funds into a Roth Solo 401K is somewhat limited, for instance Roth IRAs can not be transferred.(#2) One should not ignore the "tax dog", I assure you the compromises between tax deferred qualified accounts, RMDs, Medicare IRMAA, SS, etc is confusing. 

For instance, I have a property that started as a HH; when rates increased, re-fi’ing wasn’t an option, but the property had a layout and zoning that was conducive to adding an ADU—which I did, greatly improving the property’s cashflow.

Fort instance, Zillow and its affiliates control over 70% of the market; which more than fit the definition of a monopoly.