Wireheading as a Possible Contributor to Civilizational Decline

Also, your concern about some kind of disaster caused by wireheading addiction and resulting deaths and damage is pretty absurd.

Yes, people are more likely to do drugs when they are more available but even if the government can't limit the devices that enable wireheading from legal purchase it will still require a greater effort to put together your wireheading setup than it currently does to drive to the right part of the nearest city (discoverable via google) and purchasing some heroin. Even if it did become very easy to access it's still not true that most people who have been given the option to shoot up heroin do so and the biggest factor which deters them is the perceived danger or harm. If wireheading is more addictive/harmful it will discourage use.

Moreover, for wireheading to pose a greater danger than just going to buy heroin it would have to give greater control over brain stimulation (i.e. create more pleasure etc..) and the greater our control over the brain stimulation the greater the chance we can do so in a way that doesn't create damage.

Indeed, any non-chemical means of brain stimulation is almost certain to be crazily safe because once monitoring equipment detects a problem you can simply shut off the intervention without the concern of long-halflife drugs remaining in the system continuing the effect.

You make a lot of claims here that seem unsupported and based on nothing but vague analogy with existing primitive means of altering our brain chemisty. For instance a key claim that pretty most of your consequences seem to depend on is this: "It is great to be in a good working mood, where you are in the flow and every task is easy, but if one feels “too good”, one will be able only to perform “trainspotting”, that is mindless staring at objects.

Why should this be true at all? The reason heroin abusers aren't very productive (and, imo, heroin isn't the most pleasurable existing drug) is because of the effects opiates have as depressants making them nod off etc.. The more control we achieve over brain stimulation the less likely wireheading will have the kind of side-effects which limit functioning. Now one might have a more subtle argument that suggests the ability of even a directly stimulated brain to feel pleasure will be limited and thus if we directly stimulate too much pleasure we will no longer have the appropriate rewards to incentivize work but it seems equally plausible that we will be able to seperate pleasure and motivation/effort and actually enhance our inclination to work while instilling great pleasure.

I think it's worth making the distinction between reward hacking, pleasure wireheading, and addiction more clearly. There's some overlap, but these are different concepts with different implications for our utility.

The whole ideological subtext reeks with puritan moralism. You imply that we exist to make humanity's future bigger, rather than to do whatever the hell we actually prefer.

As long as pleasure wireheading is consensual, you longtermists can simply forgo your own pleasure wireheading and instead work very hard on the whole growth and reproduction agenda. However, we are not slaves owned by you who owe you labor and financial support for that agenda. If you can't find enough people willing to forgo consensual pleasure-wireheading to build the future you want to build, consider that it may be an indicator that people don't actually see your agenda as worth supporting.

Personally, I'd gladly take a drug that eliminates all my suffering and doubles all my pleasure, even if it drastically reduced my life expectancy. Mere existence isn't everything.