Different buyer pools homeowner vs investors and the returns are definitely in the 4 units or in value adding the 2s. 

The substantial cash need for large down payment or all cash that most others don't have .

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Here’s the bottom line; unless the deal is VERY large, or the sponsor is going to syndicate a large number of deals, the investor will make more money purchasing the property theirselves with a option low to moderate interest rate loan.  

This would allow you to defer the capital gains tax, and instead of taking a large tax hit, you would be able to use the tax to invest in a nicer property/properties.

If you don’t have a large down payment saved up, don’t worry—there are plenty of options available . . .”A trusted lender will go over the various loan types with you, any down payment requirements on those, and down payment assistance programs you may qualify for.

Also will be adding two ADUs in the back to turn the whole place into a 4 unit rental.

Patio door prices can depend on the Model of Patio door you are looking for, for a standard 60x80 in white it will cost $1900.00 colors can be added, and for a patio door 72x80 the cost will be $2100.00 Outswing for a 60x80 will cost $2600.00 installed, and for an outswing 72x80 it will cost $2700.00 installed outswing with Grills for a 60x80 costs $1860.00, and an outswing 72x80 will cost $2300.00 installed.You also add blinds to all sliding and outswing patio doors for an additional charge.

Buying a large new build home can also work well as a house hack as you can charge a premium rent, and generally most bedrooms built now a days have en suites (at least in my market).  

There are large areas in the direction of the flight paths that do not have dense populations so it’s mostly a non-issue.