[ghaff]

>plus extra student loan debt

In engineering possibly not. Often tuition is paid for plus a stipend.

>If you don't come out on top, it's a waste,

I don't know. I didn't get a PhD but I did spend a couple of years getting a Masters. I didn't really use what I specifically researched but, who knows, may have helped me get a couple jobs and I enjoyed the time well enough. Of course, engineering salaries tended to be a lot lower then relative to what many CS people today consider normal so I don't think losing out on a couple years salary was a big deal.