In the long arc of American leisure and capital, even the roller coaster must eventually reckon with gravity. Jana Partners, an activist investment firm, has turned its attention to Six Flags, urging the debt-laden theme park operator to consider a sale — a move backed by an unlikely $200 million commitment from NFL star Travis Kelce. The intervention reflects a broader reckoning in the regional amusement park industry, where decades of deferred investment and mounting debt have left chains like Six Flags struggling to keep pace with better-capitalized rivals.