This is why I think there should be very few hearts towards the middle of the game and more on the outskirts.  These guys already have the middle and are making bank, they then can collect all the hearts they want and harass the people on the outskirts with no extra investment.  I think it should be the other way around..  You are getting all those coins you don't need all those hearts... at least pay for some characters.  Give newbies a chance without very much extra investment.

These guys are moving into the red area at the moment.  Can't really do much except run away.