I had been drinking coffee with butter in it for years (a european cutomer at our coffee shop showed me) Which to me makes sense milk is good in coffee, half and half better, and cream the best so heck yeah give me butter.
I recently tried the bulletproof at a shop and it is pretty good. I think I still just like butter only tho.
I'm finding it quite amazing to see how popular it yes. I guess I am not a big fan of butter so I have never wanted to try it