Where pre-K programs shine is children with diagnosable problems. Failure to have these kids in some kind of treatment can cost the taxpayer a lot money in K-12 and beyond[1]. When I was working with a 6 weeks - 3 year program in the 90's we had quite a few cases of hearing and speech problems that could be corrected in that time frame. If the kids had made it to kindergarten like that, they would have been permanently behind because of all the brain development in those years.[2] Even making sure children were given an initial screening with follow up assessments (we used the Denver Screening and E-LAP) catches a lot of things.

Yes, the other kids catchup, but the problem is some might have never have got there.

As to pre-K / elementary, if the kid does not have STEM mentors in those years then you can probably forget getting them into STEM in HS. Opinions of cool and want develop pre-K through elementary.

1) obviously providing the child a normal or at least better life

2) I was rather horrified at how much of this got by family doctors