drinking less is extremely difficult because at first it goes really well, but then it gradually increases, and then all of a sudden you're drinking to excess again. the term "slippery slope" applies here. saying no to the 3rd drink is MUCH harder than saying no to the 1st - that's why lots of problem drinkers (i'm intentionally not using the word 'alcoholic' here) just stop completely, or drink one glass of wine at thanksgiving per year or whatever.
heavy drinkers find drinking intensely enjoyable - and (subtle difference here...) not displeasurable in any way whatsoever until hangover/puke. if you aren't the kind of person who's ever drank 15+ drinks in a single night, you just have no ability to comprehend this. it's not within your realm of understanding - your personality is just completely different. or your brain chemistry is such that after 3-4 drinks, you feel terrible.
There's another reason which you didn't mention. It's not personality, and it's not that I feel terrible after a few drinks. I drink very little because the following [1] is incomprehensible to me:
Alcohol – Euphoria has been reported during the
first 10–15 minutes of alcohol consumption.
I have gotten very drunk and yet not experienced euphoria or anything similar. To be sure, alcohol has physical effects on me (e.g. impairment of judgement and impairment of coordination). But it just doesn't do anything mental, for better or worse. I'd bet that many/most of the 60% or so of people that have less than one drink a week fall in that category. I.e. to us alcohol is "meh".
I'd much rather have chocolate or sugar than alcohol. E.g. I like Grand Marnier, but that's because it has a pleasant sweet taste, not because it has alcohol. I'll drink a few beers a year, but that's because I'm doing something social, like watching a football game with friends.
it's a combination of euphoria, a slight mania, boost in enthusiasm and motivation, and it quite possibly 'unlocks' part of your personality (i.e. the funny part, since it completely eliminates your inhibitions to tell racy jokes).
so just like you said, this is why it's so hard for problem drinkers to cut down. it's just a whole different experience than a person who has a couple and then feels dizzy and wants to sit down.
I have had 15+ drinks in a single night before, but probably only on 2-3 occasions in my life (one of them being my 30th birthday, where a mostly-sober friend was keeping track until 23 drinks). So I at least know what that's like, in isolation. But my personality doesn't push me to just go and go and go.
I'm not saying there isn't a slippery slope, but I personally cannot imagine my life without at least some alcohol. I assume for the case of someone where their (excessive) alcohol intake has a huge negative impact on their life, zero alcohol sounds like a much better deal than drinking a lot.
But I still question the accepted "fact" that this is really a fixed "personality" thing. We humans have extraordinary brains and have the power to -- possibly with help -- change a lot of things about our personality and emotional state. It seems hard to believe that "once an alcoholic, always an alcoholic" is actually absolutely true.
of course it's not absolutely true. you're not wise to something everyone else is blind to - some people are totally able to cut down. the people who say it's impossible are AA people, and that's basically a religion.
but look at you - 2-3 occasions in your life - the people who have problems cutting down are doing that 2-3 times a week and are completely functional. it's a completely different personality type.
the bottom line is, for a lot of people, it's a LOT easier to stop than to 'cut down'. this isn't a magical premise. in fact i think it makes a lot of sense. similarly, for a lot of people, stopping is impossible. and that's how you get numbers like 74 drinks a week which sounds fucking ludicrous at first blush, but is in fact quite doable.
One might expect alcohol consumption to be roughly normally distributed, but clearly it is not when the top 10% is so far off the chart. Imagine what it would be like to drink 74 drinks in a week. I've been a heavy drinker at times, but that amount blows my mind. And that's just the middle of the top 10%. I love me some booze, but that amount is so far beyond what I would consider enjoyable that there would have to be something seriously, irrationally wrong with me to partake to that degree on a regular basis.
That's what addiction is. It's like asking why someone with OCD can't simply not wash their hands. It's mind bending to even imagine for someone who hasn't had that experience. I've dealt with obsession and compulsion at times in my life (not as a disorder), and I know how hard it is for me to modify habits and fixations. True addiction is some next level shit.
I can understand why it's difficult for you to imagine how a person could be unable to stop with just one drink. It's similarly difficult for a non-depressed person to understand why a depressed person is miserable even when things seem to be going well, or for a neurotypical person to understand why an autistic person is freaked out by seemingly minor stimuli.
These are, however, all things that have been extensively studied and documented and affect millions of people. It's not necessary for you to be able to really get inside the head of an alcoholic, but that shouldn't keep you from accepting that this is simply how things are for some people.
heavy drinkers find drinking intensely enjoyable - and (subtle difference here...) not displeasurable in any way whatsoever until hangover/puke. if you aren't the kind of person who's ever drank 15+ drinks in a single night, you just have no ability to comprehend this. it's not within your realm of understanding - your personality is just completely different. or your brain chemistry is such that after 3-4 drinks, you feel terrible.
if so, be thankful.