There’s some truth in what you say. And it may have occurred much earlier than the exploitation of fossil fuels. There’s a good argument to be made that once we began dwelling in larger communities (say 175+) and required organisational structures to help us solve the ‘problems’ of such living arrangements, differential access to resources arose giving rise to power/wealth structures and the inward-looking perspective. Smaller population units rarely, if ever, display such negative social behaviour.