You're just looking at how much an obese individual might be able to eat, not at all the other shit an obese individual has to put up with:
loose skin like do you think our skin just springs back or something no, no a very obese individual will have loose skin that just won't tighten up with time, and that loose skin can lead to medical issues of its own even after the excess fat weight is gone not to mention the psychological pain of having all that loose skin hanging around, or the literal pain of running or doing other active things with loose skin trying to flap around
anyone you knew at your fattest will compare fat you to present you. You just want to be present you, you want to put fat you behind you, but oh no no people must remind you at every turn that you were, like, really, really fat once. There's no other you without fat you - can't talk about an interest, a hobby, anything without somebody first mentioning how you were really bloody fat once.
replacing clothing over and over again, waiting until your clothing is literally dangling precariously until you buy something new from the thrift store because you can't afford the constantly shrinking wardrobe.
nobody noticing your weight loss, I mean as an individual who was relapsing in their eating disorder I was glad it took people so long to notice, but an individual who was actually trying to be healthy about things? Discovering that nobody notices when you've lost 25, 50lbs can be an immediate motivation-killer.
you're still hungry - your stomach and mind need to learn to accept feeling hungry and ignore false signals, along with unlearning all the thoughts and behaviours that got you to that weight in the first place
there are often a number of related psychological reasons for a person becoming obese, and those reasons fight back as they attempt to lose weight. It's not just fatlogic keeping many obese individuals obese - fatlogic is sometimes the tablecloth an obese individual hides the elephant under in hopes that you (and they) won't see it's in the room.
you can still thoroughly fuck yourself up if you do it wrong - rapid weight loss in obese individuals can lead to medical issues - painful gallstones, for example, that may lead to gallbladder removal.
people think it's easy for you to lose weight, discounting your struggle to maintain a new regime, and judge you harsher when you slip up despite sometimes encouraging those fuckups.
No, it's not easy for an obese individual. It's not easy or fun for them to drop their calories from a really high number any more than it is for a smaller individual to drop their calories from a lower number. But unlike the smaller individual, they get to battle a whole lot of demons and hurdles while everyone judges whether or not they're putting enough effort into their weight loss attempt.