10 LOC/day is ridiculous. Think about Brad Fitzpatrick, Fabrice Bellard, John Carmack. They would never accomplish anything like they did with those 10 LOC.
You have to have dedication and really good text editing skills. Being smart is nothing if you can't write code fast enough. Good skills with tools like shell, debugger, version control are important as well.
Another problem is that dev collectives these days tend to bully and punish those with higher performance. There are several reasons for that 1) most devs do an absolute minimum just not to get fired 2) job security is a thing, you won't make your project look too simple or complete as this might end your contract 3) at least 90% of hype is from idiots and by idiots. Idiots are a heavy tax on any engineering 4) frameworks, tools and methodologies are often designed for a different scale 5) ceremonia, overcomplication of development processes, treating devs like anonymous, interchangeable units
I'm male in my 40s with a CS degree. I work from home most of the time.