Curious, have you considered some level of fractionalized investment (i.e. realtymogul, arrivedhomes, etc)? 

I got my lady on board and she started house hacking before I did, cutting her living expense to a fraction of what they were so she is able to do more of what she wants and having more money in the bank at the end of the day to buy.... more real estate!!

You would be forcing yourself to keep the property forever or reducing your buying pool to a fraction when you go to sell. 

You are paying top dollars for a CPA when you can get a consultant to charge you a fraction of it. 

Even though you bid up the purchase price you can typically get properties for a fraction of what they are worth.

I think depending on my end goal someone may suggest something different.Your income goal is very large and is something only a fraction of real estate investors ever aspire to.

Most investors suggest house hacking your first deal to get your feet wet and to learn how to be a landlord while paying a fraction of the mortgage. 

Lots of ways to skin the cat in this game and turn key is the easiest for most people to wrap their brain around.. just like you said you were having a hard time wrapping your brain around sub too... that's only because its a fraction of the market and generally done by folks more advanced in the business like a Mike  who do real estate more for a living than passive investing  a lot goes into doing a successful sub too..

I have many times been able to purchase a 4plex for a bit more (fractionally more downpayment) than a SFH.

I don't think I'm interested in a real estate syndicate or fractional ownership.I have a few properties of my own (a few single family, duplexes, and small multifamily) with some decent equity between all of them, but not nearly enough to provide a 25% down payment for a 2-10 million dollar multifamily property.