How should one think about the mitzvah of writing a sefer torah when all the organisations that he is associated with have a sufficient number? particularly about using funds for this purpose versus tzedaka or talmud Torah?
KVCT
Joel Rich
You view mitzvah 613 the way you view all mitzvos. I.e. you have an obligation to do it.
Nowhere does it say that you need to hand it over to an organization. Actually, if you do, you may have to redo the mitzvah. (You can ask a shul to house it for you. Never relinquish ownership.)
Personally I took a few lessons in Sta"m, wrote a megillah and 9 years later (about 20 years ago) I finished writing my Sefer Torah. I keep it at home (as I saw some of my Rabbeim do) and I lein the Sedra with it on Friday. (This makes me concentrate on the vowels carefully during my daily maavir sedra.)
Randomly neighbors borrow it, and during COVID-19 it was very popular.
So, just do it. 
- Danny