Government spending is decided by Congress and the President, who are not poor people. There is a convoluted selection process in which rich people (donors) select the pool of candidates from a group of rich people, and then they let poor people vote on which of the rich people selected by other rich people they would like to have make decisions for us.
On a practical matter it is clear poor people do not make decisions because poor people want things like universal health coverage, but we do not have that.
Government spending is mostly decided by huge corporations, firstly the arms industry. If poor people controlled our budget we wouldn't have throngs of homeless people in every city in the country.
I’m fairly sure studies of voter sentiment & positions vs. legislative activities and executive priorities do not back up this guess.
I see the homeless living on their tents, the inner city blacks and the white unemployable rednecks gnashing their teeth in unison: "Don't you dare buy a single F-35 less to give us some fucking stinking doctors!"
That's exactly how it is, a perfect democracy.
Government spending on the other hand, is mostly decided by poor people (majority of voters) who are more worried about tomorrow than 1000 years from now.