In my opinion no. They lose to much value as soon as you purchase them. You are better off waiting and buying them in the secondary market. If I speculate in coins I buy key and semi-key dates with the intention of holding them from three to five years. Good luck.
A few years ago proof sets seem to be a loser, but since 1999 they have been hotter than....... Check prices on some of the newer sets, its unreal. Most of these have doubled in value in just a few years. Will they continue?? For now they're a good deal. I buy all of them but don't plan on selling so to me it doesn't matter. They're still beautiful works of art.
Greg