Part of the "invest in your future through buying a house" is a notion of investing into your own safety, as contrasted to renting. Rents may go up unsustainably, but your house is still yours. Nobody can evict you from your house for not paying rent. A house is a relatively liquid asset, so if something really demanding happens, you can move and downsize, unlocking some of the wealth invested into the house. If you rent, you can also move to a cheaper place, but it won't free up a lump sum.

So the idea of "investing" is not purely speculatory.