You won't get rich from video poker even if a machine pays 100%+.  At a fast 600 hands per hour, and $1.25 per hand ($0.25 x 5 coins), that's $750 wagered per hour.  If you play perfectly (no mistakes) and realize your 0.77% advantage, that's $5.78/hr. on average.  You'll also need several thousand dollars of capital to fund the losses you'll suffer while waiting to hit the royal flush.  Yes, if you were capitalized you could play at higher denominations, except 100%+ machines are rarely found at anything but quarters and below.
Video poker is a very volatile game, about four times as much as blackjack. In any form of gambling, short-term results mostly depend on normal mathematical randomness (what some might call luck). However, in the long run, results mostly depend on skill. If you play a game with a return of 100.76% perfectly, that does not mean that you will have a 0.76% profit every time you play. The 100.76% is an EXPECTED return. Much in the same way, if you flip a coin ten million times, the expected number of tails will be five million, but it is unlikely you will hit five million on the nose. Actual results will vary significantly from expectations, but the more you play, the closer your actual return percentage will get to the expected return.