My mortgage went from $5,200 a month to $6,850 a month.Rocket is saying they can refinance my loan down to 5.34% rate but charging me 14k for buy down plus an extra 5k for fees and appraisal(19k total cost rolled into the loan).  

Ok, done, you want to buy. 

It's been several years since I have used bigger pockets, even though I paid for it. We flipped several houses since last time I used it and when I originally started paying for the pro membership, we wanted to get in...

That is where we find the best value and can often buy at a discount.

Rate is about 9% with no extra fees. 

Tourism is down and supply is sky-high, so I’d be extra cautious and strategic about buying a home for short-term rental near the theme parks right now.

A single vacancy can wipe out a full year of extra rent, so protect the yield you will have.

So let's say the seller has a mortgage for $80,000 and the buyer agrees to buy the house for $100,000 with $10,000 down.

The math does not support paying off a mortgage earley as @Theresa Harris explained.If you grandfather had bought a house in 1960 brand new for $15,000 would you have wanted him to pay that off faster or to take the extra money and buy some CocaCola shares for you?

I think as a buy and hold investor.