Simple economics, supply and demand. 

I recently had an estimate of $20,000 to create a basement egress window and I put my foot down and told my GC that I was going to rent the excavator, and we found much cheaper supplies, and were doing the project ourselves.

I know that I can write my travel, supplies, and food expenses off of my taxes while on that trip.

These provide stability and regular income, which can be crucial in retirement.Cash: 5-10%Keep some liquid assets for emergencies and short-term needs.Consider these additional points:Diversification: Spread your investments across different sectors and geographic regions to reduce risk.Tax efficiency: Consider the tax implications of your investment strategy, especially with your high net worth.Regular rebalancing: Adjust your portfolio periodically to maintain your desired asset allocation.Professional advice: Given your high net worth, it's advisable to consult with a financial advisor who can provide personalized recommendations based on your specific situation and goals.Risk management: Consider your risk tolerance and adjust the allocation accordingly.

What about repairs, supplies, and other expenses?

Request reports for maintenance, accounting, etc. on a more regular basis if you want updates.

You'll still leave a lot less than the 20% down payment needed for a regular investment property, but you should expect to leave some capital in the deal.

In others experience is this return worth the risk given Multi-family environment ie supply, interest rates, project specific risks, illiquidity risk, and more specifically the Preferred Equity subordinated tranche risk (this sounds like just a Mezzanine loan without recourse).

@James Hamling thoughts on supply vs. demand and rate lock-in? 

You are subjected to regular section 8 inspections, but as a good landlord you'd want to keep your properties up to standard anyway.