Hmm. It isn't a bad thesis. It is clear and specific. However, you'll need do several things to make it work. First and most importantly, you'll need to define "material love." What does this mean?
Then, you'll need to take the other factors that lead to their destruction into account. For example, they are not nearly as good at control and manipulation as they think they are. Is that because of their "material love"—or independent of it? In either case, it contributes to their destruction. Likewise, where do things like the loyalty of others to Lear fit into this thesis?