Why Gamble
You put out the question everyone else has already answered here. You advise that you will figure out what you are doing wrong when you lose money !!! WHo is going to tell you that your shoulder is dropping or you are curling your wrist. The guy taking your money certainly is not going to tell you. Yes, that means they should take lessons so they can figure out when they are making mistakes and try to salvage the game they are currently in and not figure it out when they get home that night with empty pockets.
How much money do I need to lose to Archer or Efren before I realize I will never beat him!!! The same happens if you are playing a local shortstop and you keep losing. You don't know how to win because mechanics are sloppy, aiming is poor, stance is wrong, and worst of all, you game strategy and safety play is piss poor.
And think about this !! Tiger Woods has a coach, the best golfer on the planet !! And don't kid yourself about others never having coaches... They might not have been certified instructors, but some of the top players had somebody tell them how to play. Efren Reyes learned how to play one-pocket in Chicago which was taught to him but some of the great one pocket players in Chicago, like Freddy the Beard and others. So even Efren had to take lessons from players more experienced them himself. Now he is now one of the best one pocket players on the planet. Should Efren have lost his bankroll first before he talked to Freddy and the others ? Well, if he was a sucker he would have, but Efren is no sucker.