Improving societal trends are more important than individual efforts

individual efforts need to be aimed at collective efforts
A common mistake made by future-caring people is to think that by "doing their part," they'll be able to change the collective trend.

In fact, if "doing your part" is taking time away from changing societal trends, then the opportunity cost is so large as to be worse than useless.

When it comes to changing societal trends, it's paradoxically more important to get society to change than to change yourself.

Parable of the stony islands

Imagine a world consisting of only a few islands of stones, where people subsist on a diet of fish. Chasing live fish is hard, so people like to fish by throwing stones to hit nearby fish. But predictably, this makes the islands smaller over time. You decide it's important that future generations have land. Imagine two courses of action you could take:
  1. You stop throwing stones and begin fishing in the laborious fashion, even though this gives you no time to campaign to change others, and take consolation that at least your actions are not contributing to the loss of the stones. The sensation of moral superiority may give you further consolation.
  2. You place your full energies on changing societal trends, and only rely on the laborious method of fishing until everybody has agreed that it is categorically unacceptable for anybody to live in a way that hurts the future. Unlike the moral comfort you obtain from the first approach, this approach can leave you feeling embarrassingly hypocritical. But your primary concern is the welfare of future generations, not your own self-image, and you persist.
This parable is an example of why changing society's trends is more important than changing your own behaviour. Changing your own behaviour only helps if it changes the behaviour of society summed over time.

N.B. The two choices in the parables are extremes. In many real-life situations, such as forgiveness or setting an example, the antithetic maxim be the change you wish to see in the world becomes a necessary step for changing the group's trends.

The use of fossil fuels

A more modern example of the parable of the stony islands might be a person who wants society to stop using fossil fuels (perhaps because they feel that the fuels should be saved for future generations in case of emergency). If this person refuses to use any fossil fuels — and to walk everywhere instead of using modern transportation — consider several possible effects: