OK, well let's imagine your typical philosophical materialist. He (it usually is a he) thinks that everything is made of matter, including his friends, his feelings of love, and his consumer goodies and gadgets. Now, if this materialist is an intelligent and thoughtful person, he will value and like his friends and feelings of love more than his consumer goodies. Indeed, he will be aware of all the studies showing that accumulating consumer junk doesn't make you happy and that family, friendship and community are the key things. In other words, for him, some material things are much more valuable than others. So it in no way follows from his philosophical materialism that collecting consumer goodies is the way to go or that environmental destruction is to be pursued.
As for the idea that this version of materialism is too narrow, I guess you'll want to add in elements like no free will, no meaning, no value, no purpose, psychological egoism and so on. If you do that, then yeah I can agree with you that materialism is a bad thing, but that's hardly surprising, since you've just built all of that into the very definition of materialism!
And yeah, of course I agree that ideas sometimes matter and can influence people's behaviour. Examples of this would be the idea that animals are mindless machines and we're not, that we have souls and black slaves don't, or that there's eternal punishment waiting for you if don't believe X. The question is, do metaphysical theories like materialism, idealism and panpsychism have a big influence on people's behaviour. I suspect not. But almost everybody here disagrees with me.
The difference between me and most people here is that they think ALL ideas matter a great deal whereas I think only SOME do. Indeed, I would also argue this is one of the main differences between New Age/paranormal thought and professional philosophy. Professional philosophers (even religious ones like Plantinga and Van Inwagen) realize that some issues in philosophy are of merely 'intellectual' interest.