Depending on your current career path, up to a certain age it's entirely possible to switch careers entirely, even to something that makes concrete use of skills acquired from another career (so it's not a complete restart). Built-up capital or some other means of remaining self-sustainable for a period of time could allow you to return to school in something completely different.

I'm not speaking from experience though; I can guess that this type of situation would be difficult. But when saving, balancing the return on investment with the accessibility of the funds seems wise.