I still disagree with some points (and impressions) you made, but bleh it's not very productive for both you and me to get into a debate.
Since I don't follow gravure (and the general non-JAV celeb circle in Japan) I'd ask your expertise. Take a typical year, how many gravure idols are active with a 10 year career? How many active gravure idols can make a decent living from her modelling income only? How many new ladies who are 25 years or older can debut in gravure and get a 6-month guaranteed contract? Take a typical year in the past, say 2015, make a list of the top 10 idols in gravure, how many are still active in gravure after 5 years (2020), how many are still in celeb circle (say transitioned to J-pop, J-drama etc) in 2020?
I truly don't know these answers and would defer to you. But the same question for JAV is .... well... not great, I'd admit not great. But the reality is not so cruel either. Entering JAV industry carries a very serious stigma, it's not a secret. But if you take a girl X, who's very hot, and if she choose gravure, sure that makes sense. Or if she can accept the stigma, choose JAV, with or without trying or considering gravure, well it's perfectly understandable too.
Linking JAV to suicide is a false topic also, yes some JAV idols ended up in prison or murdered or suicide. But considering suicide rate for Japanese women in many different sectors are also very high.