Like the OP, my own experience belies the general trend.
My parents had 3 kids, all born/raised in the WT cult religion. All 3 of us graduated from college. I am the only one out of the WT cult religion. One of my siblings has a graduate degree. Did that valuable graduate degree help my sibling to really question our upbringing and indoctrination? Did it really help in vetting the ideas and prejudices foisted onto us by our parents and their peers?
No. Not that I've evidence of such, anyways.
I believe OEJ gives a good analysis in citing the power of immersion. I think my mom (despite being a fan of college), doubled down on the 'immersion' so as not to have her kids walk away despite the education. I found it suffocating. My siblings conceded. My mom's strategy was 2/3 effective.
Another family from the hall had 2 young sisters. One was academically inclined, very smart & studious. The other one -ahem- academically 'contraindicated', shall-we-say...? Well. the smart one went to college, graduated, got a high-paying professional job, and is still a devout JW. The other one barely graduated high school, drifted through an assortment of menial jobs, and finally became an entrepreneur of sorts. I believe she finally carved out a modicum of success for herself, and..oh, yes...this is the one that exited the JW cult religion.
Another case, I would say, where the mom was an absolute nutcase & tyrant. Total 'immersion' (haha). One person finds it intolerable, and another is broken. Who can predict these things?
Anecdotes aside, I have no doubt that the general trend is true. Religiosity wanes while education waxes.
Just kinda wish my family wasn't so much an outlier...