There is little correlation between student outcomes and money spent per student. Outcomes depend on how the system is structured and whether the right incentives are in place. When education policy is largely determined by the teachers unions, you can see worse outcomes because resources get spent on higher teacher salaries instead of improving services to students. Here is an academic study that looks at the relationship between student outcomes and spending and suggests that spending more on teachers has no statistically significant effect on outcomes:
https://www.sciencedirect.com/science/article/abs/pii/S0272775715000242If more money is to be spent it has to go to more than just lining teacher's pockets.