Can I just post another tale?
I have a friend who gained weight as an adult over a 10 year period due to mobility issues (sudden onset, at size 8) prescribed steriods for those mobility issues. BMI became 42, around 20st, size 24.
She was referred to 'weight management' at local hospital and stayed on the list for nearly 5 years due to incompetance during which time, despite losing 3st & 3 lots of surgery to try to help her mobility (which failed) she was also diagnosed with sleep apnea. Eventually, she was able to progress on the pathway by seeing a psych x 1 & 1 group session on 'healthy eating'. No info was given about surgery at all.
She saw a surgeon once, out of area as her area don't do surgery. He told her there was a slot free in 4 days time 'before funding tranche expires'. He suggested roux en y (bypass). She had the surgery.
She was then sent back home (150 miles) with poor comms between out of area and home NHS. She didn't get the B12 loading shots (indeed didn't get any B12 for a year). She became severely anaemic (now needs IV iron infusions & B12 shots every 8 weeks). Although she lost weight she felt ill. She lost her job. Only 1 annual follow up.
She has been meticulous about following online advice she found herself and has now lost a total of 8st from her highest weight (3 prior to surgery, 5 from surgery).This has been maintained for 4 yrs.
She regrets it. She feels exhausted all the time. She still has sleep apnea. Additionally she lives in a small rural village. Her ongoing meds label was printed: 'post bariatric surgery' & the person working in the local chemist noticed & sadly gossiped. She had a bag of dog faeces put through her letterbox with an anonymous note attached saying that she had 'taken money that should have been used for cancer victims' (this was pre covid). That affected her MH a lot.
So, knowing her story quite well I'd say:
It's NOT an easy option (she was unlucky her NHS area was so awful)
You have to be sure nothing else will work to put yourself on the surgical table and there are risks.
The recovery is not fun - baby purees for weeks.
Small portions of some foods only and vitamin supplements for life.
You have to be vigilent to maintain it - there is a 'bounce' in weight.
It is socially 'unacceptable' to have the surgery: you may be 'judged'.
You may feel exhausted and generally below par for years after.
BUT .. everything the OP has said about the statistics of signigficant and long term weight loss is correct. And it DOES 'save' the NHS money long term. We have a very disordered relationship with food in the western world. It would be good to see money invested in this so that fewer people need this type of invasive surgery. For those that do, there should be less judgement, better information & follow up.