Short term use only. Bitcoin now is the best way to keep and save after it dropped in price.
I don't think so. Some stable tokens are reliable enough to be used for the long term purpose. You can see how USDC was very reliable enough to be used as long term hodl to prevent the bearish trend to come anytime. I think that it's not all of stable tokens were not reliable for long term. Some may have very good fundamental that makes the stable token can be used for the long term purpose.
but not all stable coins are good for the future and I will take the example of the UST coin.
previously, UST or Luna was known as a stable coin and had high interest in all markets. there are so many big investors who save money in Luna coins so they are not affected by the fluctuating crypto prices. but in reality Luna was like throwing away coins and the price went down very deep. and after that incident, some big investors were afraid to keep big money in stable coins.
but for me keeping money in USDT or USDC coins is a stable coin which is safe and has a very good reputation for the future. but it's all back to each one to start research before putting money into some stable coins