Even if all their patrons are poorly informed and being tricked into giving them money, from the graph they showed the majority of their patrons still decide to stay if you compare the curve before and after they turned the project into a gaas model, which means the commercial model may not play a decisive role here.
I assume by "gaas" you mean gotcha?
There really isn't any indication that this is a micro-transaction game on Steam or their website, at least when I subbed. Even on their Patreon, they don't really mention it. Only some people make comments about it.
I feel like that graph is kinda bullshit when you consider you have to pay an accumulated amount of $36+ through Patreon before you get a serial to play the game. And most people don't know that prior.
So after you sub your first month you either walk right then or you sub upfront on a high tier for next month or you pre-order a year at discount or you sub at minimum for 9 months per month,
all prior to being able to play the game.
Which means their monthly sub counts are inflated and can't be directly correlated to anything specific.
The least of which is subbscriber satisfaction or quality of game/devs, which imo is more valuable information and what I assume was the point of them posting the graph in the first place..