So my final point is that we can't always blame kpop fans that decide to stan or being fans of successful groups, as they will have a longer career without disbanding after just 2/3 years if not less.
This is absolutely true imo, it's easier to support a "stable" group with an agency that can support the career of its artists. The situation of certain idols is unfair and sometimes talented people who deserve more attention don't get noticed or can't gain a fandom because of the lack of resources and connections of the agency (and that obviously compromise the stability of the group) but at the same time the industry is oversaturated and so many groups keep debuting, there's a lot of small agencies too, that decreases the possibility of success even in more "fair" conditions.