Sure, they can change their mind and become a biologist. But in doing so, they throw away the two years. They have to start college from zero, because their trade-school classes don't translate into college credits.
You can start college at 20 as easily as at 18. The problem is that you get nothing for the two years (except, I suppose, you can work as an electrician to pay for college, instead of working at McDonalds).
You can start college at 20 as easily as at 18. The problem is that you get nothing for the two years (except, I suppose, you can work as an electrician to pay for college, instead of working at McDonalds).