You played the first hand right. A high pair should be held against a 3-card royal flush. If you had a 4-card RF (or a 4-card St Flush) you would break up a high pair. Sometime the wrong play will give you a big win. It's all probabilities, but over the long term (thousands of hands) you will be ahead playing the optimum strategy for the game.

Congratulations on the Royal!

Sometimes the probabilities work in strange ways. I've been playing VP at Wynn since yesterday afternoon playing Double Bonus on a 5 line machine and have hit 4 different 4-Aces for 800 coins! This is a hand that usually comes up once a trip after 12-15 hours of play. You can rejoice when something good like this happens but you can't do anything to make it happen. Well, yes you can help it along in certain instances... in DB, believe it or not, the correct strategy for a dealt FullHouse containing 3-Aces, you throw away the other pair and go for the 4-Aces. I usually doesn't work and you end up with just a Triple rather than a FullHouse, but I've had it work 3-4 times over the years.