With regards to traveling nurses, I was mentioning them as a potential tenant pool if I decide to purchase a STR, as an alternative or supplement to vacationers as occupants. 

Nelson Nash developed the concept in the early 80s but the product the concept utilizes has been around for much, much longer.Since you brought up term insurance (which is temporary w/ no cash value accumulation or dividends), oftentimes a policy will be supplemented by term insurance in the form of a rider that allows one to increase their death benefit such that they can store more cash in their policy without triggering IRS MEC limits and therefore be subject to tax hits.The concept and its value proposition is incredibly misunderstood (and sadly often abused) but the reality is it works.

A line of credit can also be a useful tool to supplement your business.

Unfortunately you're not paying him enough (and he's not charging himself enough) to stay on your project all the time so he has to create supplemental income.

Rather than wasting it or leaving it in a bank account I'm interested in starting my own investment business to supplement my real estate sales. 

Also, many clients are going to a 1-man office staff that is supplemented with a kiosk.

I am certainly not a tax expert, but fwiw, I just looked at my closing statement from the purchase of a Brooklyn multi-fam and as purchaser, I paid the following taxes:Transfer Tax Additional Transfer(mansion)taxTransfer Tax Supplemental NYC(mansion)taxMortgage Tax 1st mortgage

Of those 20 projects, we BRRRR 8-10 per year, and the flips supplement the money left in the BRRRRs.

I’ve been thinking about supplementing my investing with something like this in the near future.

While you won’t get rich doing this it could be a good fit to have supplemental income to purchase your first few deals.