Bookies can't do much about this as the odds reflect the form, if they would lower too much then it would mean too big odds on handicaps for the other team so they just go along with it, it's not a very profitable scheme, it looks a lot of capital and there are just a few teams with which you can play, you're barely beating the stock market but yes, it's positive.
Can you explain what strategy is "hidden" in this table? And by the way, from what I see - 10 teams are profitable, 10 are unprofitable. It seems that there are more profitable teams in the top, but not so much to make a profit from this or to be sure that this will be the case every year.
In certain years, such declines as those recently seen by Napoli, Bayern, Liverpool would ruin a player using such a strategy, wouldn't they?