It is a gamble and I know the past few years were stable, but we are going into an unknown lending period.

You'll need to run the numbers, but since no one knows what the rate will be in 12-36months, you will always have to speculate (read that as gamble) on an ARM.

If you are asking specifically what appreciation impact will the NGA have on a specific neighborhood, I do not think anyone can answer...It's a bit of a gamble but it seems reasonable to think the NGA will bring some appreciation to neighboring homes.

You can do a cash-out refi on your house and blow the money gambling.

In searching existing STRs, it is very clear this happens in practice, but I am not willing to buy a property and gamble that we can do an STR.

Not likely but it’s a gamble versus a scalable business approach.Develop an operating agreement.  

I decided to gamble on appreciation and overbid on a duplex that will have good cash flow in Oak Park after losing another all cash deal (I bid all cash, over asking and was outbid by a buyer with similar terms with an offer “well above” mine on a different property in the same neighborhood. 

If you're counting on appreciation, then you're gambling - doesn't matter where we're at in a Real Estate cycle.

They were gambling that the yield curve wouldn’t invert like it did, but then it did, and hard. 

thats the bay area.. .. will your prop do that who knows.. but its only a short term gamble so you gamble 3 to 10k over a few years and see what happens.