Tether can be both pumper and dumper.
Pump up BTC price with Tether. Use Tether to buy BTC. Sell BTC for USD (or hold onto it - it's free!). Doesn't matter that the Tether either never actually existed or were seized by governments.
Pump up BTC price with Tether. Use Tether to buy BTC. Sell BTC for USD (or hold onto it - it's free!). Doesn't matter that the Tether either never actually existed or were seized by governments.