Thanks for the chapter!
Explanation for reset marathon really lacking. A Reset Marathon is when a player attempts to get something but fails, resets the character to start over from scratch, rinse and repeat over and over until get that something. In this case MC was going to foolishly kill himself to 'kill' his character, reset meaning he'd start over at the beginning area with new crystals but without Silent, and use the crystals to try to get an ideal summons while Rinsing and Repeating until satisfied. In PTW games (Pay To Win where more money you put in the better stuff you get like special items, characters, etc.) the chances of getting an exceptional character is slim, and usually deliberately set as a fraction of a number rather than a whole number like .2 or .005 so can honestly say there is a chance (just like the lottery) but extremely unlikely to win. Hence a Reset Marathon where use the crystals to summon, usually fail so reset character by first killing him (may need to uninstall and reinstall the game,) and try again several hundred times in an attempt to overcome luck with summons through numerous attempts.
Reason said MC foolish is he has no way of knowing whether he can reset like the game or if it's permanently game over if he dies. Despite actually being there he's too stuck into the altered rules and physics of the game. For starters, I doubt the game's Silent has that much personality, can talk, protest about value given, or even interfere with actions of a player like stopping him from killing himself. Somehow I doubt those NPCs are just going to disappear after the fight. As for his Resetters comment it probably means that people who usually get those summons wouldn't put much value in or want to keep them and so would reset for something better. However, he's assuming that this is a quest like in the game and that their levels or skills haven't been upgraded to allow beginner players to easily defeat them. Guess we'll find out if he's right but worst case is they've leveled enough to be able to beat beginner players and summons at the least.