So what is it that combines property investing and currency mining?

I surely cant.Someone paid $700,000 a room for a Waikiki Hotel recently-  its absolutely not make sense.It is most likely foreign investors that bought up the property. 

There still is lots of growth in digital currency ethereum seems to be something I have heard about from a lot of younger people.

Account ClosedIt is certainly do-able to invest in rental properties/notes as a foreign investor.You may be subject to ECI, FDAP or FIRPTA as a foreign investorECI = effectively connected incomeFDAP = Fixed, Determinable Annual or Periodic IncomeFIRPTA = Foreign Investment in Real Property Tax ActAs a foreign investor; you may be required to apply for an ITIN and file a 1040NR.If you invest through a partnership vehicle; the partnership may be required to withhold on you during the year in which case you would have to file a tax return before you get a refund if you overpaid(or owe more if underpaid). 

Last time I checked the burden of compliance with FIRPTA including withholding funds from the foreign seller is on the buyer.

There are avatars, different "portals" to games, a fake currency (that parents buy for real money of course) etc.

Honestly, getting INTO NASA is hard (especially as a foreigner), but once in, it is pretty "easy"... 

At this time, I'm personally looking at cities in the Carolinas, and I absolutely love Atlanta (GA), but foreign investors are driving down cap rates and its difficult to find good deals over 100 units, but they're out there. 

Now I just need to find a nice location where I can continue making purchases over the years, a good deal, a trustworthy property manager, and potentially some means of financing suitable for foreign investors (although I do have some contacts in this final area already).

A solid investment portfolio typically includes a diverse set of investments which could include hard assets such as real estate, gold/ silver, cash and intangibles such as stocks, bonds, currencies.