>>714988727
They will update the game with new training scenarios, and new scenarios tend to give you better results than the last.
Of course giga whales will be better than you and turn the game into easy mode. But once you get yourself used to the flow of the game and have a decent set of support cards, the career won't be posing any difficulty (with some exception for special cases) for the average players.
At that point your hardest opponents would be other players during PvP, and Master Challenge - a set of superboss umas similar to legend race but wayyyyy harder.