The game "high risk high reward" don't make sense

The game has this motto, but it makes absolutely no sense
The biggest rewards are all for group content, where the risk is infinitely lower, group dungeons, for some reason, are much better than solo dungeons
If that motto were true, solo activities in the bz would be extremely rewarding
And there is guild content that, depending on the content, can achieve zero risk

What do you guys think, is my logic correct here?