While the syndicator will also benefit from selling at a profit, the person investing in this model is typically less interested in the upside profit.

Wont that impact my profits immensely?

From there I can sell after a few years for a nice profit.

I could easily walk away with 100K in profit afterwards.My issue is, if I sell it, I'm going to get hit with a tax bill unless I dump the money into a new home, correct?

If any of the variables go haywire, it could eat up your entire profit and possibly cost you money. 

They are going to use the profits of the sale to build an apartment over the existing attached two car garage OR build a tiny house on my property.

What is your desired profit? 

We then discovered homeaway and rented an “unrentable” property for 120 nights and will actually profit on the house this year for the 1st time in 13 years.

Its rental real estate, at its core it's a profitable business.

Open a HELOC to access remaining equity (80% LTV), and re-invest on other assets (out of state properties, private lending, etc)In the end, you have an asset like other people mentioned above, that will continue to appreciate in the long run, and you have access to the equity to reinvest and make more profit.