Are poor people stupid? Obviously a lot of people think so. They mean to protect the poor by denying them the ability to work for a low wage (minimum wage laws), or to live in a frugally-built house (building codes), or to force them to educate their children (compulsory schooling), and to compel everyone to pay for the education of the poor (school taxes).
If poor people really are stupid, then a different set of policies is needed than if poor people were merely poor for the moment. If poor people are stupid, then you would expect them to remain poor because of their stupidity. This could be discovered by tracking a sample of poor people, to see if they stay poor. That's been done, though, and only a small minority of poor people are poor from year to year.
The majority of poor people drift in and out of poverty. Sometimes they're young people just getting started. Can't afford a house, maybe can't even afford a car. Don't have much work experience, so they have to work at "starter" jobs. Other people might be able to earn a higher income, but are prevented by their life situation. Perhaps they're single parents, perhaps they're on probation and tied to a location with a poor job market. Perhaps they're divorced and sharing custody? Other people might have lost their old job and are temporarily poor while retraining themselves for a new career.
Policies which assume that these people are poor because they're stupid are not just philosophically wrong, they're actively harmful. A person of ordinary intelligence must be presumed to be able to make the best of their choices. If we remove choices because we don't want them to make stupid choices, we make it harder for them to pick the best choices. For example, if we force all new houses to be of a fixed minimum quality (building codes), then we force these people to live in older housing not covered by building codes. It's very presumptious to say that that's best for them. We should allow everyone the most freedom to choose, even the minority of poor people who are actually stupid. Controlling the actions of adults degrades their judgement and turns them into moral infants.