There are a few ways to gain stamina in the game. For example, guild chests award stamina a lot...
The quests pose a challenge for the player ~~ I think quests are alright, but I dislike the lvl requirements and such, I just wanna get on with the game.
There are also a few things that are fun to do without stamina, like Rag or Baal and etc, and guild wars are interesting, too.
~You don't need money for power. ~