I think you make a valid argument. Money can always be "spent" to help those in need or to address issues like pollution, over-population, etc. Thanks for taking the time to read and comment.
The difference is real spending vs. real investing. A lot of next generation technologies require a large infusion of capital to get things started, in the past this has been provided by the very wealthy and/or government .
A good example of this is the entire computer industry, which was started by the British in World War 2, simply to break German coded messages. The money, scientists and equipment had no real purpose at that time, other than for spying and war.
War is a bad thing, however it sometimes drives innovation that changes our society; computers, nuclear power, space exploration, etc. I am in no way advocating war, but history is history.
If the same money was spent on charity, perhaps we would only now be seeing computers entering the realm of science fact. maybe not.
Creating new industries and opportunities helps everyone, directly and indirectly. Shifting industries like mining and smoke stack manufacturing to space, will definitely help the environment on Earth. Just like the computer revolution changed everyone's lives and continues to provide opportunity for millions, so will space. We need a jump start and large capital infusion to get a real permanent space station built, but once it is operational and profitable, we will wonder why it was not done earlier.
Perhaps most importantly, having a lot of technology and "eyes" in the sky, looking for profitable asteroids to mine, could save our planet. Having technology in daily operation that can capture, move and detect large space objects, perhaps will be able to save us from a "Killer Asteroid Event", that is 100% coming to Earth sometime in the (distant, I hope) future.