Stat cap changes for your job rank. Here's a post on Zam where someone did some testing based on Vitality/Mind. So, for example, the max at level 20 is 76 points. If you're playing your level 50 Gladiator, and you've got 174 points in Vitality, and you switch to your level 20 Pugilist, you'll only get the benefit of 76 points.

But it's your character. Have fun with it. Play around. You can always reallocate your stat points in the future.