That changes things - but it's still a massive investment of time as you say.
I'd think 50 hours per nominal week x 40 weeks x 3 years for a BEng or equivalent. Apart from anything else, to keep going through all of that, you need a real passion for the subject (and maths!).
So, basically, are you interested enough to keep going through 6000 hours of study? Ultimately nobody can answer that but you.