This is true: it would be wise to be honest with yourself on this point. I've personally read more textbooks since graduating than I did in college; it's not impossible, but it is very very hard to stay focused in self-study.
And then they utterly faily, because self-study is not one of their pre-established habits.
If you make a schedule mimicking a college curriculum (during the weekday, with a lunch hour, 15 minute breaks, etc) like you would with an actual class, and use the "tuition money" to pay instead for a good desk with ample room for notes and a solid reading light, then I bet almost anyone could do a college education on their own.
It's all mental, and in my experience, mindsets can be changed with the right training. It's like learning to brush your teeth, except you're an adult now.