"There aren’t a whole lot of government investments that boast better dividends than preschool. Numerous studies have demonstrated that society spends between $7,000 and $9,000 per preschooler, but sees at least a two-fold return on that investment. The largest benefits are usually in crime savings — one study from 1980 found that every $9,000 spent on preschool in Chicago saved the city $42,000 in crime-related costs, and that every dollar invested saw a return of $3.39 in earnings and tax revenue from these children who matured into adults who abided by the law, pursued higher education, and earned high salaries." 

https://www.fatherly.com/parenting/data-preschool-pre-k-education-kids