The parental success being hereditary is not merely random, it is because parents put a lot of effort into making sure kids do end up the same. Intervening when things go wrong is one of ways how it happens. Changing school when peers or teachers are bad is also how it happens. If you don't care and kid don't care and you are fine with it, the kid will grow up into person that don't care when when left on own devices.
The tutor makes difference when preparing for tests that decide which school you go to. You being yourself when you actually finished the degree and you being yourself when you did not is not the same for jobs that require degree. In many jobs and societies, credentials, the degree and school and network do matter. Which is why those with resource push for those credentials.
When you don't know high school math well, you will have hard time in those STEM classes that require difficult math. They are difficult enough for students from good schools, those from bad schools were literally drawning. It makes difference between finishing it and having access to those jobs and not finishing it and not having that access. I don't know how in your school, but ours kicked a lot of people out on these.
You know who is in worst economic situation in USA right now? Students who did not managed to finish college, but do have debt.
Parents can make a small short run difference through massive effort, if they really want to. It just doesn’t matter in the end.
What you can make a long term difference in is how fondly your children remember their childhood, if their parents were there, loved them, and were happy, rather than tired, stressed and angry.