They’re responding to her as if she’s a fully healthy and stable person who is escaping from the prison of the conservatorship, so cheering her on - not as a clearly ill and vulnerable person who (while the conservatorship was clearly all kinds of wrong) pretty obviously still needs some significant help.
Would any of us be fully healthy after what she has been through? No one could come out of that situation without some issues!! That doesn't mean that she's clearly ill though.
Lots of people go through breakdowns, I'm sure we all know some people who have, neighbours, distant friends etc...and perhaps their breakdown was a secret and we're not aware because they got the right help they needed at the time and came out the other side.
If they'd been treated like Britney had then they wouldn't have had any chance to recover properly from the breakdown and get back to normal life.
That doesn't mean that she's not stable. Perhaps she has mental health issues like complex PTSD which can of course cause issues, but that doesn't mean that she's not stable
I agree she needs significant 'help', she needs 'help' to come terms with what has happened and everything with her family, betrayal, trust etc. but for anyone who thinks she needs significant help based on what she posts on instagram is just like back in the day when women got diagnosed with hysteria.
Perhaps she just loves being an exhibitionist, loves the attention, perhaps it's a fuck you to her dad. I do burlesque and I know lots of women who would have posted similar to Britneys latest post!