Not having the energy to pursue an idea is a useful filter. It means pursuing the idea is theoretically exciting but not actually exciting enough to actually pursue. That's most ideas for exceptional people and pretty much all ideas for most people. Machine learning and time series analysis pass the filter. Keep riding that bus for now.

Your day job of doing dull research is just a day job that advances your career opportunities, and having a PhD statistically increases a person's career opportunities. Grad school often ends with a 'death march' to just get the damn thing done. The only thing that is guaranteed is that not finishing means no PhD. Short of severe mental health issues, there's not much upside to quitting with only a year left.

Good luck.