[Simon_O_Rourke]

You'll hear lots of glib remarks that doing a PhD "sacrifices earnings potential today, in order to have less earnings tomorrow". My wife did one after five years working in a telecoms multinational, and it was a marathon with lots of ups and downs along the way.

The main thing, w.r.t. tech roles is that a lot of the more advanced, and possibly higher paying, ML roles require a PhD in a related field. So if that's what you want to do afterwards it's an option.