I know lots of parents who have dc who board or very recently boarded.
From 5 DC that currently board, 2 aren't happy and the other 3, I think are okay. They all started boarding at 13 ish. They are all between 14-17. The ones that aren't happy, one is looking at taking them out completely and the other , they are looking for an alternative school, possibly closer to home so they can come home more often on weekends.
Other 4 DC I know who have left boarding (now aged (19-27). Two are thriving, with jobs, travel, girlfriends, typical young persons social life etc.
One is diagnosed bipolar, has had a lot of therapy, has really struggled but I think is now much more settled but hardly in contact with parents now. Obv, don't know whether boarding issues in therapy.
The other one is the saddest, despite coming from the most wealthiest of all the families, their DC has gone down a destructive spiral of drugs, in and out of the most expensive rehab from America to Austria. You name it, the parents have thrown all the money they have at it. They don't know where they are half the time, living in some squalor in Amsterdam one minute to a bedsit in Thailand. Very chaotic lifestyle. It's been heartbreaking.
All the families above are quite different, parenting styles vary, cultures, wealth, family dynamics. I've known some of the kids from when they were toddlers, and in hindsight you can sort of see which dc, boarding is probably not the best choice.
My dc don't go to boarding. I'm glad they haven't to be honest. From my anecdotal experience; think wisely.