I think a lot of it depends on whether you're struggling or not, and what your needs are. Some people can thrive quite happily on a surprisingly low income. If you're living on disability benefits, the chances are high that the money won't be enough to meet your needs. How many people you may need to support, especially including children, will also make a difference. I think there's a strong poor = unhappy assumption, so if you're on a relatively low income but completely content and not having any trouble with your finances, you are less likely to think of yourself as poor.