People like to get their money sooner rather than later. 40 years ago it was probably not a big focus for the people running Exxon to potentially get a lot rich

People like to get their money sooner rather than later. 40 years ago it was probably not a big focus for the people running Exxon to potentially get a lot richer 40+ years in the future, but rather being busy getting "rich enough" in the next few years. Most companies(which are just peoole) doesn't start thinking too far in the future until the curves of those "next few years" point abruptly downwards.