I eventually did study part time for a degree, mainly out of belief that it might help with future career opportunities, but also because I might enjoy it.
I got a 1st, with honours. TBH, the only part I truely enjoyed was the final project. The rest was mildly interesting at best, and a bore at worst. I found 80% of it easy, 10% difficult (maths), and 10% challenging (the final project, but only because I made it challenging).
In retrospect, I don't think it's really made any difference to my career, as I'd proved myself long before getting the degree. I don't necessarily regret it either though - maybe the most useful thing was getting me into the groove of reading academic papers, which had benefited me greatly, both work-wise and in my personal life (health issues).