re: Poker & Tournament Skill vs Buy-In
You are absolutely correct that bankroll management is key. $100+ MTTs will always be around, but your bankroll may not be if you're careless with it.
That said, the competition at $5-$25 is fairly similar, but as DancingNancie says, it ramps up quite a bit when you get into the midrange stakes and beyond. In addition to facing more resistance preflop, post-flop play also becomes much more of a challenge. Things you could usually get away with at lower stake MTTs, like limping, playing OOP, or playing top pair with average kickers get punished.
I'd say the best way to prepare for those stakes is to learn how to play different styles if you don't already. Good players at high stakes actually pay attention and will pick apart one-dimensional strategies.
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