Here’s the thing though – “experts” say that we have approximately 10-50 years before the Earth can no longer sustain the size of our population, and most scientists agree that at some point in the next 50 years, the damage to the environment will be so bad that we are unlikely to be able to reverse it.
With regards to both issues, many governments prefer to simply ignore the facts, rather than proactively tackling said issues.
Therefore, it is critically-important to the human race that we consider the alternatives and the obvious alternatives are habitation on another planet or space stations.
But those things are never going to happen if we don’t make advances in space technology, and we’re not going to make advances in space technology if we don’t invest in space technology… Which is why things like space tourism are essential to our future.
Sure, for the first few decades it will be only the uber-wealthy going into space for nothing more than fun – but every trip into space will mean more money put into the industry, and a bunch of geeks somewhere in the world are going to be using that money to advance the technology used in space; which in turn means that we are going to be one step closer to habitation on another planet or on a space station.
So at the end of the day, whilst the environmental impact of space travel is significant, “the ends justify the means”.