People use formula for as many reasons as there are babies.
I have a friend who formula fed all 3 of hers almost from birth. With #1 she had a forceps delivery, a vaginal haematoma, massive bleeding, 3 surgeries to try to remove/close the haematoma, almost a week in intensive care and 15units of blood transfused. She was severely anaemic despite the transfusions and her milk never came in (milk is a blood product, if you are very compromised in that area you will need a lot of help to get a good supply going). Her #2 she BF for a few days, but her #1 is ASD and would stand screaming about 1 foot from her whenever she nursed, she ended up putting him in front of the tv in a stroller while she fed, which was obviously NOT the best thing for him, nor for her because it made her feel like crap, nor for the family with exhausted self-hating mum and square-eyes #1.... With #3 she began, but since her #2 is only 1 and #1 is only 3 she has a LOT on her plate. And so she went to FF quite quickly because pumping was too time consuming and BFing wasn't realistic with 2 other tiny kids, one of whom is SN, when she COULD NOT afford to be the only one who can feed the baby.
She is one of my closest mama-friends, and i love her (very healthy, certainly as healthy as mine) kids.
Another friend was definitely going to BF no matter what. Her boy was born with a cleft palate and hair lip and could not physically latch. She pumped and fed him from a special bottle for 4 months, until he had his surgeries, hoping he would feed from her after them. He never wanted to latch and by 7 months his bottles had formula in them as her supply had dried up.
Another mum i know wanted to BF but her whole family and her DH brow beat her about it. Both the grandma's wanted a "go" at feeding. Her DH felt he wouldn't be able to bond properly without feeding the baby. Her best friends all formula fed and looked at her like she had 2 heads when she suggested she might BF. She tried for a day. It was hard (it IS hard for a lot, possibly most, women, especially in our culture where it is not the "norm") and instead of supporting her everyone told her to get over herself and FF. And she did.
I am a sex abuse survivor and i know another woman who didn't BF because of the flashbacks of abuse it gave her. She was a child/young teen when she suffered the abuse, she has gotten a good life together for herself, but despite many years of therapy the flashbacks don't stop. Should she BF and associate her tiny babe with molestation, fear and guilt? Should she have waited, possibly indefinitely, for the flashbacks to be "cured" before she had a baby? She did neither. She FF instead.
I had very strong ideals going into motherhood, and i too flexed them by projecting them onto the world. BFing went great for us, i was so lucky, until DD hit 4 months and my thyroid gland, which had been under attack from my immune system (undiagnosed) since before my pregnancy, suddenly all but gave up. My milk dried up. I pumped. I took herbs. I rested. I saw about 5 different people from hospitals, LLL, NCT, anywhere i could think of. I did everything i could think of at the time. My milk dried up anyway. By 7 months DD was on FF. And it nearly killed me. But you know what? No-one died. It wasn't the holy holy ideal i had set for myself, but in the event it turned out to be a perfectly acceptable REALITY to live in.
This time i am braced for similar, i have a massive support network in place, including a few pregnant friends who with luck will be able to provide EBM should we need it, but if i have to face using formula again i will. It is fine to judge inside your head, but be careful you don't let it colour your opinions of someone's whole life. If i had looked at the bottle of FF and dismissed people as potential friends because of it i would be missing out on knowing one of the most gentle, loving, HAPPY families i know. And it would be all my loss.
Very few people get through their entire parenting career with their original ideas and ideals intact. You might have any number of plans, but you have to parent the kid you get, and that might mean that your ideas of discipline don't work at all. You might plan the incredibly healthy lunch boxes your kids will take to school, but you probably won't bin the majority of them for many years before you revisit what you CHILD thinks is good for lunch. You might have a nearby play park you can't wait to visit, only to find your child is very into stories, crayons and dolls and NOT at all into getting dirty and climbing on things. You might decide you will absolutely BF no matter what and get a baby who for any number of reasons finds it very difficult to do so.