I don’t regret my math minor but that didn’t go on the paper diploma …
I will tell my kids my mistakes and recommend that they don't "put all their skill points into math/engineering/etc" in college.
However, if you mean they shouldn't choose engineering as a major: I don't regret my CS degree at all, even though i hated it at the time. The logic and scientific rigor helps me in the most practical things in every day to day things at work by being consciously analytic.