I feel your pain. I have often, and very recently been in the same spot. One thing that helps me is to try to rationally put the suckout in perspective.

As you know in poker there are two ways to win a pot – get everyone to fold or have the best hand a showdown. When you play people who never fold, you only have one way to win, and the truth is in holdem, you’re rarely so far ahead a fish who doesn’t fold can’t catch up.

The only way to win long term against them is to keep putting yourself in profitable situations. Before you studied the game you sucked out more often, because you got your money in bad more often. The more you lose to suckouts, the more your opponents are the ones putting money in behind. So away from the table try to acknowledge that suckouts are a sign of your skill improving. While in the moment you wish it were impossible for aces to get cracked, in the broader picture when the best players always win it’s bad for the game.

The randomness in poker is necessary for it to be profitable. If the worst hand always lost, either the fish would stop playing, run out of money, or learn to play better. When their bad decisions are occasionally rewarded, they don’t see a reason to think more clearly about the game and they still have money to lost to you later.

Try to focus on what you can control – making the best decisions – and not the random luck that you can’t control.