The best person doesn't always win. Clashing styles make matches interesting, and rulesets also make matches interesting. Some people are really good at EBI or ADCC and not as good at the other. Some rare people are really good at all the rulesets. Some people are terrible at one ruleset but super good at another.

Being athletic and good at a few things is sometimes better than knowing a million moves. It's not always, but definitely sometimes. This continues off of our first point: the most knowledgeable or technical grappler doesn't always win against a grappler who is athletic and good at what they do.

You're going to lose. The less experienced you are, the more likely you are to lose. Even the best grapplers ever have lost. Lots of people hate losing, fear losing, and don't lose well, and this blinds them from the reality that losses are data, not personal assaults on your character.

There is a higher risk of injury in competition than in training. I think that a lot of people in Jiu-Jitsu are desensitized to injuries, and even more so in the competitive world. The harsh reality of competition is that there is a significantly higher risk of injury than in training. I've had more injuries in competition (or preparing for it) than in normal training, and I think most competitors are the same way. I think competing is great, but you need to understand the risks and prepare your body for a "fight".