An investment isn't necessarily something that is expected to go up in value, it is something that is expected to make you money. If I buy a house and rent it out, and the value of the house also tracks inflation, it made me money through rent. If I owner occupy I receive that money in the form of lower expenses, but that's just details.

Similarly, if my education increases my lifetime earnings by more than it cost me then it is a good investment, regardless of where in my career I make that return. The idea that my education must increase in value over my career in order to be considered an investment is very, very strange.

You can argue that these investments are frequently bad, but it doesn't make sense to argue they are not investments.