Invest in tether is not a good way for profit and you can not trade tether with real dollars. Anyway, if it is tradable, the trading fee will kill traders who want to trade tether with dollars.
OP didn't mention anything about making profit with tether. Converting your crypto to tether is one strategy to secure your profits when the prices starts heading down like where we are now.
I guess it was implied and the profits would come from the fresh opportunities and the capability of buying back the Bitcoin at a lower rate and giving it time to climb again and the process is rinsed and repeated.
I don't hold any tether though i'm fine with holding my coins and it's stressful when you have to watch the price every time just to move your coins to an exchange and back.
Most exchanges support Tether so there's no need moving one's coins back and forth an exchange.