Alcoholic Sim?

Try and set them a dislike for mixology

Tried that already, now they just make drinks angrily. 

Doesn't really sound like a bug to me. I've seen sims do this since forever. When inspired, they feel like crafting stuff more, like painting or in this case where there's a bar available it's mixing drinks. It's just the autonomy they do when in an inspired mood. When they're not inspired, I don't think I've seen them make drinks, unless they are thirsty and in those cases you can tell because they pick up whatever they make and drink it right away, rather than leaving it on the bar for others.

I don't think I've just left them to do unlimited drink mixing – I've certainly never lost thousands of simoleons. Whenever I notice a sim is making more than one drink, I just command them to do something else. Any extra drinks they've made, you can drag to a fridge and it will keep there for a long time, and they'll grab them when they're thirsy.

@DaEpicKoalaIt kind of goes along with the annoying habit of sims grabbing water. You can disable the autonomy of mixing a drink using MCCC if you want .. unfortunately it effects all bars in the game and so if you go out to an actual bar or lounge you'll have to reenable it so the bartender will actually serve drinks. One way to circumnavigate that problem is to grab the globe bar for your home and disable autonomy on that since it's it's own entity and not related to other bar types. Even though the selection is limited it does allow you to serve drinks and your mixology skill will slightly go up when using it and you'll be able to have a drink when you want and not whenever your sim wants.

While it is true that it is actually designed that way, it doesn't mean they shouldn't consider changing it. I have included a fix for this issue in my thirsttweak mod a long time ago but still I think everyone should be able to have an inspired sim not constantly crafting drinks because there is a bar nearby.

Some well-thought changes to the bar_StartCraftingAutonomously tuning would be great. I restricted mine like this which is very strikt but maybe at least something that reduces it a bit:

<L n="test_autonomous">
    <L>
      <V t="buff">
        <U n="buff">
          <V n="whitelist" t="enabled">
            <L n="enabled">
              <T>145405<!--buff_Role_Butler_NPC--></T>
              <T>12616<!--buff_Role_Bartender--></T>
              <T>192860<!--buff_Fame_Quirk_JuiceEnthusiast--></T>
            </L>
          </V>
        </U>
      </V>
    </L>
    <L>
      <V t="test_set_reference">
        <T n="test_set_reference">126907<!--testSetInstance_InteractionIsEncouragedByClubRules--></T>
      </V>
    </L>
  </L>

Yeah, this is riddic. Happens with my sims too. Especially when they are inspired.