We have a friend who son was a great student in high school, was a really good ultimate fighter, and had a good part time job. Then he went to college. Colorado state u in Ft Collins. Before pot was legal he grew pot for medicinal purpose with a friend. He dropped out of school and was high always. He lived in the mountains alone for a while and would call his sister saying he was being watched by CIA, NSA, aliens..... He moved back to Denver and grows pot again. His dad is trying to get him to move to South Dakota with him, but he won’t. He’s now into eastern religions, metaphysics,...... He’s so lost. He was such a good kids the college and pot ruined him. I still pray he finds the truth in God.
Cause and effect.
There is no way you or anyone else would know if pot caused that young man to go down the path he did.
It could have been the people he met, or the books he was reading, or any number of things put together.
Or just maybe for the first time in his life he felt he was able to think for himself and he made the life choices you wrote about.
Who knows what lurks in people’s hearts and minds.