There's always something to innovate, you just get diminishing returns. The problem is that sooner or later, the returns diminish below the profit rate of banditry and rent-seeking.

Also, there's plenty of wildly profitable innovation, but so much of it isn't politically feasible because it will hurt the profits of existing rich people whose permission you need to upend the status quo. Usually this isn't a conspiracy so much as the alternative being so completely incomprehensible in the current paradigm that it's just written off as crazy and a terrible idea.