1. If you’ve already been everywhere once.
If you already have a pile of passports filled to the brim with stamps, a travel agent could probably turn to you for advice (or maybe you should consider becoming one yourself).
2. If you’re only interested in the cheapest option for everything.
That’s what Expedia is for. Travel agents are not human discount machines. We’re in this work because we’re creative and we enjoy designing itineraries that our clients wouldn’t be able to design themselves. We don’t have a magic wand to make everything cheaper.