I think, unfortunately, your friend made some very critical mistakes that are going to cost him time and money.Here's what I see as the steps to unraveling these egregious errors:(1) Hire an attorney whom specializes in landlord/tenant law(2) Wait for the eviction moratorium in NYS to end (patience will be required here, as we're at 16 months and counting)(3) Under your attorney's advice, carry out an action against this freeloading occupant as a "licensee"  (I think it's called section 425?

Specifically for buying the only ROI for being a licensee is whatever buyer agent commission you might make with on-market purchases. 

Most single family home data is already out there for non licensees, so I don't think the access it that incredible.

You can be licensees in as little as 3 weeks, and if teaming up with a good team, can be making 6- figures in your first year, and usually double your income each year after.It’s even much more lucrative than what real estate agents make.Lastly, it’s much valuable knowledge to a real estate investor to understand the numbers, Loan guidelines, income docs.Don’t get me wrong, real estate agents have a hard job, and I would never cut it as one.

In fact, you are probably better served not to be licensed so that you do not have an implied duty to not use your status as a licensee to take advantage of the seller or the general public by buying their property for less than it's FMV without disclosing what it's FMV really is.

You'll also need to check with the same office regarding any other laws licensees need to follow when buying and selling mobile homes. 

The Agency’s investigations are complaint driven, so we rely heavily on the public, and our licensees to bring these individuals to our attention.

A license shall be obtained for the licensee’s principal place of business and shall not be transferred or assigned.

Tenant shall be charged for all repairs or replacements caused by Tenant, pets, guests or licensees of Tenant, excluding ordinary wear and tear.

These are all things that licensees and property managers have been doing for a long time.