I work really hard, but I might be an anomaly. I can't get much done in the time many people might.
My brain is bad at focusing on things, so it takes a lot of effort to engage, become productive, and then stop. There's a lot of time build up inertia, but then it's difficult to reduce that inertia as well. As a result I'm fairly inefficient by default.
I have a practice of never billing for inefficient time. I don't feel right doing it. As such, I tend to work an average of 10 hours per day but end up billing for more like 7 or 7.5. It's just a reality that I live with now.
So no, I can't get by on 5-10 hours per week. I would be fired quickly.
Although I have the knowledge to do my job well, I lack the executive function. Improving that is one of my main objectives but it's much easier said than done. I think it's the one thing that would improve my career and personal life the most.
All that is to say, there are plenty of reasons why some people work more or less. I work more than you because I'm not a productive person. I'm not a 10xer, I'm not more committed, I'm not more effective. I simply have to in order to get an acceptable amount of work done.