There seems to be a lot of us escapees about!
Re. Serena Williams, I don't know anything about her but, if she was never baptised then she isn't a JW in spite of her upbringing and isn't held to the same standards. Given her lifestyle, she won't even be allowed to be an unbaptised publisher (someone who goes out on the work before they are baptised), so it's likely that she just has a JW background or is "associated" with congregation (even that is a bit unlikely to be honest.).
Shednik, the daughter in that family isn't an adult yet so her parents still have a responsibility to look after her and provide for her. They will be expected to limit social or unnecessary interaction with her, though, until she sees the error of her ways and comes back to the Truth.
Oxford, no, there is no financial gain. Witnesses hope to ensure thier survival at armageddon. The preaching and teaching is an integral part of that. There is blood guilt to be borne (at least there used to be) for all the people who haven't heard the good news of the Kingdom, so one of the reasons for door kncking is to avoid the punishment that that blood guilt brings.
Also, at the end of Matthew's Gospel, Jesus commands his followers to go and make disciples of all the nations. It's called the Great Commission and the way JWs fulfil that is by knocking on door etc. They see this very much as proof that they are the only True Religion. In addition, THE END will not come until the good news is preached throughout the whole world, so the more doors knocked, the sooner Armageddon will come.
There is a lot of training for the door to door work. There is a meeting every week devoted to how to spread the word effectively. The training is given to children as well, they take part in the Theocratic Ministry School meetings.
I'm a bit different from the OP, Rhonda and the like in that I wasn't brought up in a JW family, I was recruited. I was a scared lonely teenager who had survived sexual abuse, rape and terrible bullying. I was living on my own in a strange city, away from home for the first time, starting uni. After the first contact, it was a couple of young girls round about my own age who were sent to folow up. They "befriended" me and I got sucked in.
My being at uni was a bit of a bone of contention, tbh, because all the other young folk were doing the whole JW thing of leaving education at the first available opportunity and dedicating themselves to the work. I wouldn't do that, I didn't leave uni. I think some of the men felt a bit threatened by having an educated woman amongst them, looking back.
I fell for it hook, line and sinker. I distanced myself from my friends and family, who were "holding me back". married my completely unsuitable boyfriend, gave up smoking, stopped going to my own church, did absolutely everything to make myself clean. I was inside for more than 20 years, but the ever changing teachings, the way people just accepted the word of the GB, even when it directly contradicted previous teachings, the way the GB tried to control even the sex lives of married couple, the denial of good in any other religion or people, and the complete lack of mercy and forgiveness wore away at me until I couldn't take it anymore. When I moved house, I just quietly disassociated myself. I took years for me to stop being terrified that I had condemned my children to a horrific death at armageddon, though.
I am back with my own church again, because I do believe in God, but there are still somethings that I am very uncomfortable with. I don't think that the effects of that level of indoctrination ever leave you really