However at this part of the story Gene doesn’t realize he was never forced to participate in such activities. He agreed to be a part of the activities because his lack of self-confidence and fear of losing Finny (the person he aspires to be), kept him from saying no.
His own insecurity in his abilities, is leading him to believe everyone is set to work against him.
All of these combined with the frustration of not being born with a talent like Finny, is what drives Gene to cause Finny´s tree accident.