"Decades" in the field referred to those starting at $30K-ish in other fields... for many PTs it would take far less time to break $100K (though some never will as you say.) And if you don't... you'll still be making a good salary. I am American but went to school internationally for another graduate degree (and now going for an OT masters) and paid less than I would have in the US, but those who got my same graduate degree in the US paid about what one will pay for a DPT in the US... with very little chance for a starting salary higher than the $40Ks. PTs will generally do pretty well. Don't be thrown by the high student debt... chances are you'll relatively quickly "make back" in higher salary what you've taken out in loans. (Not that you'll actually be paying off your loans quickly with your increased salary, but theoretically, one could.)
I'm also "non-traditional" and changing careers (to OT, not PT) and this will be my third graduate program! I've also gotten to the point where I want to enjoy my work and money is less important (somewhat paradoxically since I'll be more in debt than ever.)