Using iPhone 6 as a Personal Hotspot/Wifi for Laptop

Verizon rep told me doing this for much time with hotspot is really bad for phone. Not intended to be a router for

extended time. Said phone gets really hot and does internal damage to use it this way. He wanted to sell me a

Jetpack for $100 to use instead. a) does it cause damage over time? b) Is a Jet pack better for this purpose? Thanks!