what are you talking about? the best players, believe it or not, actually do win basically every time! luck plays a role, but tripping stretches luck too far. as far as i can think of, damage is the only thing based mainly on luck, because the same attacks don't always do the same damage. the stages based on luck (arwing lasers, falling tools) are almost all banned, so theres nothing to worry about there. even knockback direction and stuff can be controlled. take the Ken Combo. that stuff is not luck.
The best players don't always win every time. I can say that from my own matches and the matches that I've witnessed, because I've played tournament-style with people, and there are some that I've beaten who were probably better than me, and I've been beaten by people who are probably worse than me. Matches come down to making split-second decisions in the heat of the moment, and even better players end up making some mistakes over the course of a fight. If you just catch one too many bad breaks, you could be beaten by someone worse than you, definitely. I think most smashers understand what it feels like to play competitively and passionately, only to make one wrong move and lose the whole match. Now, the customary answer to this is 'well, if you made a mistake, you aren't very skilled at all, are you? You deserve to lose.' But if the choices initially appear equally appealing, and you don't know what your opponent will do, it sometimes comes down to a simple rock-paper-scissors type scenario, where you simply hope your move will be advantageous against what your opponent is planning. I think most smashers have been in a situation like that. Luck does play a part in matches, from my experience... how great a part, I cannot really tell. It depends on the circumstances.
However, playing more and becoming more familiar with the game mechanics helps to lessen the chance of a defeat, as does skill. Tripping, from what I have seen, is semi-controllable; in my matches, it generally happens when you start from standing to dashing at a very fast rate, or when you turn around to run. If you have more fluidity, this variable can be controlled, and a familiar player can avoid tripping. The more you run, the more you trip. Don't run so much, you won't trip so much. That's not to say you won't trip at all, of course, but we can't control everything.
Anyhow, that's my two cents.