This achievement can be very easy to get by getting 3 friends and yourself into a private 4-player Peg Party. (This can be done on Public or Ranked, but this solution is for public.)
1) Decide which of the 4 players will get the achievement, since the other 3 will be missing on purpose to help them.
2) Set the level to Stage 2-1, the number of rounds to 15, and random characters OFF.
3) The player getting the achievement can pick any character, but a good choice would either be Renfield for the Spooky Ball power, or Warren for his Lucky Spin ability. The other 3 players should pick Bjorn for his Super Guide ability.
4) The player getting the achievement should be able to clear the entire board with 15 shots. The other 3 players will immediately aim off to the side and clear a gap so they can easily shoot and miss every time after that.
5) Be sure that the player getting the achievement doesn't just HAVE 100k points by the end of the game, they also need to be at least 100k points ahead of the players. Once the achievement pops for the first player, decide who will get the achievement next, then just repeat steps 1-4 until everyone has it.
*NOTE* Users have posted comments saying that even though they followed this exact process, the achievement still didn't pop for them. This just means that it can be glitchy, so please don't downvote if it happens to you.
**NOTE** Also, if you downvote my solution, PLEASE post a comment explaining why, what I can do to improve it, or any other concern you may have. That or shoot me a PM.