It's impossible to separate Steve's rejection of cancer treatment from his brilliance as an innovator and CEO.
A more risk averse guy, with less of a sense of drive and infallibility would have got the operation sooner. But a more risk averse guy wouldn't have taken on the job of Apple CEO for a second time and rebuilt the company.
If a parallel universe was inhabited by 'sensible Steve' who got the cancer op immediately, I'm pretty sure that none of us would have heard of him. What sort of sensible person would continue to work long hours, if they had a great family sitting at home and a billion already in the bank? I wouldn't!
So this 'stupidity' is just the flip side of the coin of Steve's brilliant personality. Yes, he died sooner than he should have - but he also accomplished more during that time than most of us ever will.
Demi-god/paid-user, you stole your thinking from the "Tapestry" episode of TNG. But is perhaps slightly true. Dramatic, but small truth perhaps.