Because there is more risk that generally comes with higher interest rates. 

I guess they are holding you ultimately responsible for pricelabs raising rates.

But even then, seller financing is rarely substantially better than another investment they could make (including trust deed lending, which will often be at a higher rate than seller financing)In my experience, the owners who find owner financing advantageous are at the ends of their careers and are not interested in looking for another investment (other than the usual retirement funding sorts.)

I think most investors want to win on more than just the interest rate.

If you are selling for 1M after closing costs you could purchase two 500k properties in your exchange and own one cash and a mortgage on the second.

So for the bookings we get on there, I am invoicing her monthly for the cleaning fees and then 18% of the rental rates for each booking.

Currently we would be at 8.5% interest rate.  

Although the Joshua additional demand is smaller, it is closer to DFW, which means its rental rates will be higher. 

If the cash-out refinance option isn’t providing enough liquidity, you could also consider a hard money loan, though these tend to come with higher interest rates and shorter terms.

Pay the mortgage.