I mean there are two ways in which you can lock in your gains from cryptocurrency.
(1) Convert your cryptocurrency to money & transfer to your traditional bank account
One of the way of cashing out your cryptocurrency is through Coinbase. However, you would need to link a bank account to be able to withdraw it. The negative side to it, is that it usually takes a couple of day before you are able to get your cash. (~2-4days)
(2) Convert your cryptocurrency to another cryptocurrency
That is the why you mentioned, changing your other cryptocurrency into tether. However, this also means you are exposing yourself to a different type of risk.
On the bright side, the chart of Tether of rather stable in comparison to most of other cryptocurrency:
https://www.tradingview.com/symbols/USDTUSD/Because of this price stability, it is a great place to keep your “cash” while you wait for the next trading opportunity.
You need to take into consideration that there is
many unanswered questions about Tether, so do consider the risks before jumping into this. One of the main concern for Tether is that there is no legitimate audits for the longest time, and it is a red flag (definitely!)
On their website, it is mentioned that each Tether is not backed by $1 USD. Thus, when a cryptocurrency bubble arises and pops, there might not be enough liquidity in Tether and consequently, lead to its collapse.
Last thing to take note, Tether is a centralized system based on trust that can be easily exploited/ close down by the governments, which is entirely different to what the early adopters of cryptocurrency were trying to achieve and construct.
"The concept and development of a centralized dollar-pegged coin is fundamentally harmful for the crypto-market that is based on decentralization, censorship-resistance and anonymity."
Thus, there is two sides to a [Suspicious link removed]d point being: Fully Backed, Bad point being: Ability to attack the crypto-community by the media, government and banks