*He also has layers of people between him and potential clients looking to sell to him, as he has patterns of behavior that allow him to feel "big" while remaining small no matter how big his portfolio.

Yup; the overwhelming pattern that I've seen is that certain folks have experience that gives them a leg up and makes it viable.

You may need to get creative with ways to exclude people who have no financial incentive to pay up.3) No pattern of trouble with the law.  5 misdemeanors in 3 years is a pattern that shows they don't care about the social contract we agree to as civilized people, even if it is just something small like traffic tickets. 

That's the pattern in my area.

Even pre-COVID it seemed like it was a REALLY clear pattern of "hey Chris I want to refi out of the fix-n-flip loan, we went way over budget, but we might break even if we are lucky with the appraisal" from first time rehabbers (& see the ten thousand threads on this very subforum for how likely "getting lucky" with the refi appraisal is).

@Yaz Furukawa my uncle is a developer and usually gets information on building patterns etc. from town hall or state website.

I think millennials are demonstrating the exact same pattern as previous generations.

The pattern you are describing will be common trend over the next few years.

@Adrian ChuHere is one old migration pattern map... but same pattern continue even between 2014 to 2018

We typically have a few evictions per year and the pattern has been consistent for the past 10 years or so.