I'd say it's harder to quit eating badly than it is to quit cigarettes: You can live a long life without ever touching a cigarette again. But you won't get far with going cold turkey on food.
Food is also harder because a) the healthy option is more expensive and b) sugar and heavy processing is in so much of the food available that it's hard to avoid, or sometimes even detect.
Healthy food is often more expensive but there are healthy options for cheap. Rice, beans, and vegetables are all pretty cheap and can form the base for a lot of different meals. The hardest part for me eating healthy was having to relearn a completely different set of recipes
