Bought two investment properties outright in early 2000 - didn't mortgage them.
Read Rich Dad, Poor Dad on holiday in Ireland in 2003 and realised that the above properties had almost doubled in value. If I had mortgaged them at the time of purchase, I could probably have bought 10 in all and had the added value of the capital appreciation from Other Peoples Money, re-mortgaged them all and no doubt would have 30 or more by now, not 6.
Result is, I still have a day job. 
David
Long ago, below an picture of a 4-masted sailing ship in a heavy storm was added: "A ship in a harbour is safe, but that's not what a ship is designed for"