I think live-poker is differently challenging than online poker , it compliments skill-set of being patient , self-aware and social likeable person .
Online poker works for the introverted guy who is good at analyzing stuff , enjoys being alone in PC . It can however be that a person gets tired of that after doing 5+ or 10+ years even first years were great. What to do about getting tired is different question though . Personally I have done nothing about it , just not studying anymore , playing live poker sometimes etc ..
Whichever fits better live poker or online is question of personality imo . and if I have to guess many of the Euro guys just don't make enough money online anymore so they switched to live-poker and never bothered thinking too much of how its a social thing to play poker with other people . Personally I try to tolerate and get along with all kinds of people and never really feel that someone pisses me off when playing live . Something I hate is guys who try point out some rules (had a guy who told me I cant buy in for more than X amount to the game ) when I was a bit above because entering with just one chip etc. idiotism is always annoying a bit but I guess has to be tolerated for an extend .
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Being too loose aggressive and thinking one can outplay guys was the biggest mistake I made (and still make when tilted ) when playing live-poker .
Second is thinking they know how to play pre-flop / that they play a reasonable range and so on .. making too many assumptions by default and jumping into too big conclusions .
Sometimes some hands can be complete crushed when getting raised when the other guy plays a random range and has tons of off-suit hands he "isn't supposed" to have
Sometimes people bluff random merge stuff without having any idea of what they are doing .
Its very random game overall at most live-games imo. and best results probably come by being a bit tight and paying attention to stuff at the table .