I can understand the points you're making here but I'm going to admit here and now that I have had a gastric band fitted.
I was a normal size (about 9 stone 7 pounds) before getting pregnant, and just under 11 stone (10 stone 11 pounds) when I gave birth, and I am 5'3 inches. I put on LOADS when DS was tiny though, I just ate all the time, I'd phone and order a pizza after eating lunch because I felt I needed it, I ate chocolate and crisps and cake in the evening.
In desperation I went on a meal replacement plan and it worked, I got down to my pre-pregnancy weight and then I put it back on again ... I was FURIOUS with myself (still am!) I knew what I was doing was complete self destruct but I couldn't stop. I got a gastric band (went about the balloon in fact) and I was 13 stone, 6 pounds when it was fitted.
The gastric band is NOT an easy fix, anyone who thinks that it is honestly needs to live in my shoes for a day and see what it is actually like. The thing is that after the operation you can only drink shakes/soups and most people lose a lot then. I lost just under a stone in the first week and that was obviously with not as much to lose as your friend.
The thing is that the band doesn't stop you feeling hungry. I thought it did: it does not. I thought after eating a small amount I would have a nice full feeling in my tummy, like after a nice Sunday roast with a pudding. You don't. What you get it after a few mouthfuls especially if it's doughy food like a sandwich, or even something that isn' t mushy, like fruit, is THE most horrible sensation that your chest is tightening and you can't breathe ... and the only way to relieve it is to puke. The problem is you're still hungry, your stomach is still saying "feed me" ... so you have to eat SOMETHING and some foods slip down a lot easier than others.
So yes you are being unreasonable although I understand why you say these things. I think though if you have a lot of weight to lose you can feel so unhappy and desperate you just feel like you'll do something, anything ... and also because the band is not an easy fix. Trust me, anybody with a band will struggle the same way a normal dieter will: they don't just sit back and get on the scales every week and watch the numbers drop, I wish it worked like that and I once thought it did. But it doesn't. I hate mine, I wish I'd never had it done but I did and I now have to live with the consequences.