Poker Club

In the Poker Club discord, the devs clarified that this achievement counter only goes up by 1 for each bounty tournament you participate in and collect a bounty, regardless of how many bounties you collect. So don't bother trying for multiple bounties in big tournaments - go small and fast instead. Fastest way to get it is to create a custom heads up tournament with a bounty, 200 buyin, and just shove every hand (don't even look - you'll get bonus exp for the "blind bluff" to help with your level 100 achievement).

Custom heads up tournaments only have 2 people total, making for very quick games. For custom games, you can also start them early with bots - no need to wait for the 5 minute timer that PCC games have. By shoving early, you end it early. And with a 200 buyin, who cares if you win or lose.