Did PhD in a topic. Still like the topic. My advice: people over generalize from their n=1 experience of doing a PhD. There are so many differences between fields, universities, supervisors...
I actually enjoyed my PhD studies (in Algebra). "Love" would be a strong word, but discovering new interesting mathematical facts was a cool activity.
I still love the subject I did my PhD in.
I did get thoroughly disenchanted with academia though.
This was my experience. My advisor said, "You can do that, but no one will hire you." I decided I'd finish my dissertation on a topic that interested me then become a programmer. And here we are.
I only did a Bachelors in Engineering - super passionate about electronics when I started! Had zero interest when I finished - something to do with academia (and I come from a very academic family background)
How about "Never do a PhD, because afterwards you'll hate it"?
How about "Never do, because afterwards you'll hate it"?
Never do, there is no try
This is unfortunately true more often than not at least in my experience.