If you "Borrow" $100 today, and the stock markets skyrocket, you have to "pay yourself back" for amount that the stock has skyrocketed for (which may end up being much higher than whatever return you make on real estate).  

...but haven't seen anything amazing yetAnd just to clarify, by "amazing" I mean "anything that's roughly competitive with the stock market."

I am still researching but it seems that there is a flat rate of 6% income tax on investments, interests and dividends such as stock. 

I have a friend that owns a vending machine business and in a lot of cases the businesses don't get a cut of profits, but the businesses want the machine there so it will be there for customers, and the vending company supplies the machine, keeps it stocked, and maintained and keeps all the profits.

Something I learned to late is to convert them to a tax free account and make up the tax and penalty by possibly being able to invest in a place other than the stock market by having a true self-directed IRA.If I was younger and was more aware how things worked I would be much better off when, and if I did, retired early and spent my later years on retirement by having financial freedom. 

I have mine in Fidelity and Vanguard no load, no fees and I can trade stocks & ETFs cheaply if I want.At Dow 26,000 I'd be dollar cost averaging out of equities honestly. 

I’ve never added any college type housing to my portfolio for various reasons and may just continue to stock pile cash for now

In both my wife's culture and mine, landlording is much, much more common as an investing strategy than speculating on the stock market.

Right now I am trying to consider the costs/benefits of taking some money out of stocks to buy a property in Belize, with the goal being using it for short-term rentals.

A lease option is a contract to rent a property with the option to buy it later at a certain price by a certain deadline, much like a stock options.