To me, this excuse is a poor one at best now. This idea that they "invested so much time" into is a reason why they won't stop reading is kind of an addict talk.
People are entitled to their opinions. This is not me saying that they should be grateful for what this manga is. Rather I am saying "why do you keep torturing yourself?" If you hate something, you stop doing it. If you hate eating spinach or whatever food, you don't go for another spoonful. That's just nonsense.
The same people are always angry, always upset, always mad about something about this manga. Well, you are free to no read it and not be judged for not reading it. Like I said, I stopped watching Gurren Lagann and Fruits Basket well into the mid of the series because I hated the direction it was going. I stopped reading other manga as well such as Bleach because I felt it got to ridiculous and I invested a lot of time with that one as well.
If this manga really is making people that mad, then maybe it is time to stop reading it. I have no problems with the manga for the most part so I keep reading. I actually liked this chapter because it felt like the good ole days. Was it out of place? Sure, but maybe that was a good thing. It is a huge curve ball that noone saw coming and it made me laugh so hard at it.
It's like Spider-Man cracking joke to the villains he fights. Is wise-cracking needed? No, but makes things interesting and sometimes it is funny. If I was faced with the end of the world, I probably be the same way. It almost shows the character having levity and be able to handle pressure. Especially Naruto who has been under the most pressure lately. It may even keep both himself and Sakura and Kakashi from going off the deep end. It is a means to keep you sane in insane times. Hell, a lot of characters do this because it relieves the tension of the situation before them so they can think clearly. Here, Naruto was smart enough to actually use it to his advantage.
Kaguya's face....I still keep laughing. lol.
Still, it is unhealthy for people to keep doing this week after week to themselves. Especially since this has been going on for the past several months or year even. If this manga really is stressing them out as much as they express on here, then they have problems.
Plus as I said the excuse is lame. Apply that logic to everything else.
"My girlfriend/boyfriend is abusive and I am miserable, but I invested too much time to quit now." Doesn't sound to good, does it?
Hell, we can even imply it to the pairing war logic here
"Sakura should stay with Sasuke because of how much she has invested in him, despite making her miserable and abusing her."
That's all I am going to say on the matter.
It's otherwise just people that feel the story has already gone down, well they have their reasons to keep reading but if they keep on going with how bad the story has become, well their opinion most likely won't change unless we get some major chapter that deals with a big setup. The story is where is is right now and there are those who feel it's gone downwind where others are still calling it flawless. I mean i honestly feel the story is still mostly good despite the few shortcomings and otherwise bypassed mechanics that were previously established but it's still mostly good and has stuff being done. I mean this is kagyua, considered a god so if Madara was a rule breaker and people complained about him, well no suprise what kagyua does. Even then it's just well naruto and Sasuke only hold the needed powers to seal her, not outright best her. I mean the other characters still have their point too, obito is defiantly going to come back in some way in all this, but again as some people feel the story is bad now, it's their reactive opinion to how things turned out, if they didn't like it well they have their reasons, it they like it well same deal for liking it. I find the situation to be still in its early part and just started I like the notion if this super powered woman being taken down since Madara was removed, I wanted to at least see a battle unlike what bleach did with Aizen years ago being so anticlimactic. Least there is a fight for this, yes some didn't like the black zetsu mastermind stuff but I feel this didn't exactly change anything from the previous established reasons for generations if fighting and conflict and competing ideals between villages and clans, it's still in effect upon naruto and Sasuke for the final battle. I find the story mostly good with some downsides like most of what Sasuke does, some old mechanics bypassed, and just the superpower clause of they are so strong these mechanics don't apply to them fully. I am also saddened sakura couldn't do more in terms of a physical role (though she has been good in many other aspects) but I still hope her, Kakashi, and obito should get some support role in the fight or do something indirectly that helps the other 2 in the long run. But that's just how fanbases are, every fans has different expectations, likes and dislikes. Just now there are people who will always be dissatisfied, others who see it as fine, and then others like me who are mostly content, and so on with mostly good to mostly bad, etc. that's just how any fanbase is no matter the series. I mean I am content with this, but I am getting dissatisfied with one piece, naruto had one humor event today, some people frown upon it while one piece pulled this crap so much, I got sick of it aside from some of the absurdly lame powers given to some villians like soap, art, giraffe, and more. One piece was always more absurd but even that has limits to what should be done and with the plot slower than a tortoise I really find myself not hoping for some big payoff with so many prementioned events from 5 or more years ago still never having come up. I find myself just otherwise sick of waiting for the story to move anywhere important.