I raised three children, and taught high school English for 37 years. Here is what I saw:
Almost always, the more pressure you put on a child to do well, the less effective that pressure becomes over the years. I had high school students who did almost nothing, but told me that their parents were successful getting them to work in the early grades. But by high school that oversight and pressure had so sapped any internal motivation that the kids stopped working almost completely. The only exception I saw to this were kids with serious learning disabilities who really did need day to day help in coping with academic demands.
The only solution I ever saw work for a child whose own motivation had been so eviscerated by parental control was to make sure that child was in as nurturing and interesting an academic situation as possible, and then stand back.
While it’s true your child will not, then, have the grades to get into a competitive college, unless he develops internal motivation he won’t succeed in college anyway. And it’s much cheaper to have a child fail high school courses than to fail college courses. I’ve known kids whose parents pulled them through high school with pressure and punishments and tutors, and then had to watch them fail out of college—often after paying twenty or thirty thousand for that first college year.