My idea was that instead of resetting everyone at the end of every 3rd round you reset the winners when they win but the not yet winners do not get reset leaving them high on the list giving them a better chance to win the next round
in this way even mildly active players will over time build their way to the top and win
but more active players will rise to the top more often allowing them to win more rounds than their less active competitors
I love your suggestion!
I like the idea of only resetting winners. I think it would be good for those winners who are reset to get some sort of small bonus that way it is not like they are starting all the way over each time. Think of like prestigeing in other idle games.