I "play" for the authenticity of the simulation. I could care less if I sink one ship, 100 ships or no ships in a patrol. To me, a 100k club or 200k club merely turns this into a gigantic pinball game. The ones with the highest scores get to have their names on the pinball "hall of fame".
There's really no way, I don't believe, that you can make the "rules" the same for everyone. You could say that you have to get 100k in one patrol with your realism at 100%, but how do you verify that? You can have the log to show the 100k, but what about the realism level? I could get 100k in a patrol, prove it with the log, and claim I did it at 100% when it was really only 25%. I merely make the patrol at 25%, rack up my high game score, then take a screenshot of the realism screen AFTER I've reset everything to 100%.
But, to each his/her own. If high tonnage scores are what it's all about to you, knock yourself out.