Sorry, he hasn't said people want to improve their lot, he said greed and envy were good. If we did all take Boris seriously and adopt that stance, where would one nation conservatism and big society be?
Personally, I don't count being against greed and envy as moral high ground, anymore than I'd count not mugging people or not committing fraud as moral high ground. I suppose appearing to take the moral high ground can be quite easy when discussing the ethics of Boris style conservatives.
If you don't enjoy the greed, but agree with it, well that's just odd surely? Reluctantly greedy? Unavoidably greedy?