I'm a shiny new vegan. DH is as close to vegan as anything and he was the one who inspired me.
For DH- it's ethics. This may be outing because we have talked about IRL but that's fine. We lived for a decade or so in the Balkans and butchering of animals was done right in front of you where we lived. I recall we walked past a goat who was being butchered and his goat friend who was next was shaking in fear. We both went vegan then.
Then we returned to the UK we bot started eating meat. Because it came in nice little packages covered in plastic and we (or at least me) could pretend it wasn;t what it was.
For a time I would buy from our local butcher and spend more money in the hope that it was more 'humane'.
DH got to it for good way before I did. I was a keen cook and I was very intent on cultural food experiences that included meat which kept me blocked I think.
I then shifted because I have a number of auto immune conditions and when researching books like Dr Michael Greger's 'How Not To Die' and the Physicians Committee for Responsible Medicine, all the research stacked up that for my conditions avoiding animal products was a Very Good Thing.
Now, I describe it as my diet catching up with my ethics. But it was the health aspect that gave me the final nudge.
I have not gotten rid of leather etc because I don't think that it's right to dispose of anything that an animal has died for. But I most emphatically will not buy animal products again.
DH inherited from an uncle a huge case of Victorian taxidermy about 3 years or so back. Turns out it's highly collectible. So we sold it at auction for mega bucks and then donated the lot to the RSPB (most of the poor animals were birds).
So - that's my story I think.