It's been only a few months since I joined bpand already reaping the benefits by getting new insights in to real estate from experienced members.I wish there was a similar platform for stock market as well appreciate if someone can share such a platform (if any) for stocks.

However, I have $5000 right now and plan on investing in stocks for four years, and then buy a duplex/triplex wherever I get stationed.But afterwards, could it be possible to take out a $3 million loan?

Doesn’t matter is the assets are cash, stock, real estate, gold or quite honestly even your car!

I've used Capital One and Discover along with a HELOC.Also, it kind of depends on where the stock market is at. 

But someone with no visible means of support might also be a millionaire who inherited the money, won the lottery, or cashed out stock options from a start-up, and now wants to take time off.

A lot of very intelligent investors will tell you to do so and I wholeheartedly would not blame you for taking their word over mine, however, the way I see it is let's say you buy a blue chip stock and it goes along its projected path...I don't see that as a good preparation to suddenly buying stock in riskier companies.

They will lend up to 50% of my stock portfolio value. 

We used this, along with selling a lot of our stock, peer-to-peer, and other financial accounts to focus on real estate. 

Seems right on track with stock market margins. 

I wouldn't save one big stock pile of money then start making many purchases though.