With all this said, I know this isn't a strategy that's very popular on BP, in reality we can't predict market values of a new build several years out due to unforeseen industry changes (regulation, interest rates, etc.).

While Mexico encourages short-term rentals, they are (strictly) regulated if not outright banned in the most popular US destinations (that is when they are not already banned by the HOA).To partly compensate for that, the US has the advantage of the mortgage.

I am actually considering doing a laundromat in a lower income area - Not sure if it can be done - zoning, new construction, sewage, water etc BUT it would be immensely popular.

In many markets, buying in the winter and selling in the spring can be a sound strategy, as there tends to be less competition from other buyers during the colder months, and spring is a popular time for buyers to start looking for new homes.However, it's important to keep in mind that the real estate market is complex and dynamic, and there are many factors beyond seasonality that can impact supply and demand

But they are very popular right now and tons of investors swarming to buy, build, and invest in them They also have additional costs to build and manage compared to flex space such as additional doors, dividers, and overhead (on-site manager etc).So I’m wondering, with a similar client base (and even shorter terms, often month to month) why is flex space such a bad investment?  

I've seen cool modular homes like Method Homes and other popular green buildings that aren't your traditional small eaved manufactured homes.

(Freddie's Small Balance Apartment loans are popular these days, but min. loan size is $1M. 10-year rate is back down to 4.5%).

I have been looking downtown around popular areas like Mass Ave.

S&T Bank is a pretty popular lender for investors here.

FHA loans are a popular financing option for HUD properties, but there are also other loan programs available that may be a better fit for your needs.