Indeed.
When I did 10 T16 rifts wearing a max rank Boon of the Hoarder, I ended up with 1,386,347,503 gold earned. Empowering a GR150 (apparently) costs 343 million gold. Completion of a GR gives approximately 1/3 of the empowerment cost back as the reward, i.e. the net cost would be 229 million gold per GR150. That means running the 10 T16 rifts, that on average earn you 35 GR keys, provides enough gold to empower just 6 of 35 GR150s.