Then we would be profiting a clean $2k a month from just this property alone and still have money for a down payment for a house hack. 

What other industry dealing with hundreds of thousands of dollars of people's money lets people become licensed in three weeks and no formal education? 

There are other considerations like limits, at-risk money, etc.

Most 2nd position lenders will want the investor to have skin in the game (invest their own money) AND be paid a double-digit return.When you purchase property, you ALWAYS need to have reserves, but in this scenario, you really need to have reserves since you will need to make 2 large debt payments every month.

A lot of new investors think they would be making a lot of money.

Usually we have a few thousand dollars each year to invest after we max out these accounts (and it usually just goes into a taxable brokerage account where we use it to buy Berkshire Hathaway or Markel or some other stock that does not pay a dividend).That extra money was actually how we ended up buying this duplex - thought it might be a good way to diversify our investments.I was wondering if I could use net income from our duplex (assuming we have net income, and by net income I mean what we report to the IRS) to fund a solo 401k or some other kind of tax-advantaged plan?

I am an active investor buying properties cheap good deals all deals must be at least 60% below market for fix N Flips any higher than that I have Zero interest it's no money in the deal.

I got my materials money back and everything I paid painters, etc..

An example of this would be mixing your personal money and LLC money in the same bank account.3.

For the most part, I have been steered towards private or hard money loans rather than traditional lenders.