Stuck on and with Earth

I like science fiction, but have costing concerns about warp-drive.

In your typical science fiction film or series, the heroes travel around planets and galaxies. Let's say it costs $10 billion to get a spaceship between planets, just on running costs. That's the amount raised by a million people producing a non-consumed surplus of $10,000 per year. So the whole planet of six billion could produce enough for 6,000 one way trips per year, assuming everyone wanted to pay for them. Even with 1,000 people travelling on a big spaceship, it is clear that only a small proportion of the world's population would get to travel on them.

So people are going to be staying on Earth for a long time. And (here's the morality bit) let's all look after this planet of our's and not ruin it with global warming and stuff.