Stablecoins are necessary when there's uncertainty surrounding the market, traders who would want to secure their funds against any sudden downturn will be safe with stablecoins.
Let's hope that stablecoins retain their price for the foreseeable future. After all, there are some stablecoins (like DAI) which depend on algorithms to succeed (not backed by USD reserves). Perhaps, exchange-backed stablecoins like Gemini Dollar and Binance USD have better chances of retaining their price of $1 per coin across the crypto market. For once, there was a stablecoin named "NuBits" which promised to be worth $1 per coin. It had a mechanism where the burned supply of NuShares maintained the price of $1 per NuBit across the market. The concept failed, and now 1 USNBT is worth a lot less than 1 USD. I'm afraid this could happen with most stablecoins that are not backed by real USD reserves.
While I agree stablecoins prove to be a great solution for a bear market, they're not perfect. It's best for a person to sell his/her coins into real USD and save that money in a Bank account to prevent any further losses. Until the crypto space becomes widely regulated by governments in the mainstream world, we cannot have a guarantee that stablecoins will retain their price for the foreseeable future. As of now, the best-performing stablecoins on the market are bitUSD, Binance USD, Gemini Dollar, Tether, DAI, and TrueUSD. Time will tell us whenever the idea of stablecoins will prove to be worth it over time or not. Hopefully, these coins would maintain their value of $1 USD per coin so that investors could trust the crypto market. Just my thoughts